diff --git a/cmd/sbox/sbox.go b/cmd/sbox/sbox.go
index e69a930..6459ea1 100644
--- a/cmd/sbox/sbox.go
+++ b/cmd/sbox/sbox.go
@@ -27,6 +27,7 @@
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -51,6 +52,8 @@
 	sandboxDirPlaceholder = "__SBOX_SANDBOX_DIR__"
 )
 
+var envVarNameRegex = regexp.MustCompile("^[a-zA-Z0-9_-]+$")
+
 func init() {
 	flag.StringVar(&sandboxesRoot, "sandbox-path", "",
 		"root of temp directory to put the sandbox into")
@@ -238,6 +241,48 @@
 	return &manifest, nil
 }
 
+func createEnv(command *sbox_proto.Command) ([]string, error) {
+	env := []string{}
+	if command.DontInheritEnv == nil || !*command.DontInheritEnv {
+		env = os.Environ()
+	}
+	for _, envVar := range command.Env {
+		if envVar.Name == nil || !envVarNameRegex.MatchString(*envVar.Name) {
+			name := "nil"
+			if envVar.Name != nil {
+				name = *envVar.Name
+			}
+			return nil, fmt.Errorf("Invalid environment variable name: %q", name)
+		}
+		if envVar.State == nil {
+			return nil, fmt.Errorf("Must set state")
+		}
+		switch state := envVar.State.(type) {
+		case *sbox_proto.EnvironmentVariable_Value:
+			env = append(env, *envVar.Name+"="+state.Value)
+		case *sbox_proto.EnvironmentVariable_Unset:
+			if !state.Unset {
+				return nil, fmt.Errorf("Can't have unset set to false")
+			}
+			prefix := *envVar.Name + "="
+			for i := 0; i < len(env); i++ {
+				if strings.HasPrefix(env[i], prefix) {
+					env = append(env[:i], env[i+1:]...)
+					i--
+				}
+			}
+		case *sbox_proto.EnvironmentVariable_Inherit:
+			if !state.Inherit {
+				return nil, fmt.Errorf("Can't have inherit set to false")
+			}
+			env = append(env, *envVar.Name+"="+os.Getenv(*envVar.Name))
+		default:
+			return nil, fmt.Errorf("Unhandled state type")
+		}
+	}
+	return env, nil
+}
+
 // runCommand runs a single command from a manifest.  If the command references the
 // __SBOX_DEPFILE__ placeholder it returns the name of the depfile that was used.
 func runCommand(command *sbox_proto.Command, tempDir string, commandIndex int) (depFile string, err error) {
@@ -313,6 +358,12 @@
 			return "", fmt.Errorf("Failed to update PATH: %w", err)
 		}
 	}
+
+	cmd.Env, err = createEnv(command)
+	if err != nil {
+		return "", err
+	}
+
 	err = cmd.Run()
 
 	if err != nil {
diff --git a/cmd/sbox/sbox_proto/sbox.pb.go b/cmd/sbox/sbox_proto/sbox.pb.go
index 7c84f2c..271039c 100644
--- a/cmd/sbox/sbox_proto/sbox.pb.go
+++ b/cmd/sbox/sbox_proto/sbox.pb.go
@@ -14,8 +14,8 @@
 
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0
-// 	protoc        v3.9.1
+// 	protoc-gen-go v1.33.0
+// 	protoc        v3.21.12
 // source: sbox.proto
 
 package sbox_proto
@@ -116,6 +116,13 @@
 	// A list of files that will be copied before the sandboxed command, and whose contents should be
 	// copied as if they were listed in copy_before.
 	RspFiles []*RspFile `protobuf:"bytes,6,rep,name=rsp_files,json=rspFiles" json:"rsp_files,omitempty"`
+	// The environment variables that will be set or unset while running the command.
+	// Also see dont_inherit_env.
+	Env []*EnvironmentVariable `protobuf:"bytes,7,rep,name=env" json:"env,omitempty"`
+	// By default, all environment variables are inherited from the calling process, but may be
+	// replaced or unset by env. If dont_inherit_env is set, no environment variables will be
+	// inherited, and instead only the variables in env will be defined.
+	DontInheritEnv *bool `protobuf:"varint,8,opt,name=dont_inherit_env,json=dontInheritEnv" json:"dont_inherit_env,omitempty"`
 }
 
 func (x *Command) Reset() {
@@ -192,6 +199,129 @@
 	return nil
 }
 
+func (x *Command) GetEnv() []*EnvironmentVariable {
+	if x != nil {
+		return x.Env
+	}
+	return nil
+}
+
+func (x *Command) GetDontInheritEnv() bool {
+	if x != nil && x.DontInheritEnv != nil {
+		return *x.DontInheritEnv
+	}
+	return false
+}
+
+type EnvironmentVariable struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// The name of the environment variable
+	Name *string `protobuf:"bytes,1,req,name=name" json:"name,omitempty"`
+	// Types that are assignable to State:
+	//
+	//	*EnvironmentVariable_Value
+	//	*EnvironmentVariable_Unset
+	//	*EnvironmentVariable_Inherit
+	State isEnvironmentVariable_State `protobuf_oneof:"state"`
+}
+
+func (x *EnvironmentVariable) Reset() {
+	*x = EnvironmentVariable{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_sbox_proto_msgTypes[2]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *EnvironmentVariable) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*EnvironmentVariable) ProtoMessage() {}
+
+func (x *EnvironmentVariable) ProtoReflect() protoreflect.Message {
+	mi := &file_sbox_proto_msgTypes[2]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use EnvironmentVariable.ProtoReflect.Descriptor instead.
+func (*EnvironmentVariable) Descriptor() ([]byte, []int) {
+	return file_sbox_proto_rawDescGZIP(), []int{2}
+}
+
+func (x *EnvironmentVariable) GetName() string {
+	if x != nil && x.Name != nil {
+		return *x.Name
+	}
+	return ""
+}
+
+func (m *EnvironmentVariable) GetState() isEnvironmentVariable_State {
+	if m != nil {
+		return m.State
+	}
+	return nil
+}
+
+func (x *EnvironmentVariable) GetValue() string {
+	if x, ok := x.GetState().(*EnvironmentVariable_Value); ok {
+		return x.Value
+	}
+	return ""
+}
+
+func (x *EnvironmentVariable) GetUnset() bool {
+	if x, ok := x.GetState().(*EnvironmentVariable_Unset); ok {
+		return x.Unset
+	}
+	return false
+}
+
+func (x *EnvironmentVariable) GetInherit() bool {
+	if x, ok := x.GetState().(*EnvironmentVariable_Inherit); ok {
+		return x.Inherit
+	}
+	return false
+}
+
+type isEnvironmentVariable_State interface {
+	isEnvironmentVariable_State()
+}
+
+type EnvironmentVariable_Value struct {
+	// The value to set the environment variable to.
+	Value string `protobuf:"bytes,2,opt,name=value,oneof"`
+}
+
+type EnvironmentVariable_Unset struct {
+	// This environment variable should be unset in the command.
+	Unset bool `protobuf:"varint,3,opt,name=unset,oneof"`
+}
+
+type EnvironmentVariable_Inherit struct {
+	// This environment variable should be inherited from the parent process.
+	// Can be combined with dont_inherit_env to only inherit certain environment
+	// variables.
+	Inherit bool `protobuf:"varint,4,opt,name=inherit,oneof"`
+}
+
+func (*EnvironmentVariable_Value) isEnvironmentVariable_State() {}
+
+func (*EnvironmentVariable_Unset) isEnvironmentVariable_State() {}
+
+func (*EnvironmentVariable_Inherit) isEnvironmentVariable_State() {}
+
 // Copy describes a from-to pair of files to copy.  The paths may be relative, the root that they
 // are relative to is specific to the context the Copy is used in and will be different for
 // from and to.
@@ -209,7 +339,7 @@
 func (x *Copy) Reset() {
 	*x = Copy{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_sbox_proto_msgTypes[2]
+		mi := &file_sbox_proto_msgTypes[3]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -222,7 +352,7 @@
 func (*Copy) ProtoMessage() {}
 
 func (x *Copy) ProtoReflect() protoreflect.Message {
-	mi := &file_sbox_proto_msgTypes[2]
+	mi := &file_sbox_proto_msgTypes[3]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -235,7 +365,7 @@
 
 // Deprecated: Use Copy.ProtoReflect.Descriptor instead.
 func (*Copy) Descriptor() ([]byte, []int) {
-	return file_sbox_proto_rawDescGZIP(), []int{2}
+	return file_sbox_proto_rawDescGZIP(), []int{3}
 }
 
 func (x *Copy) GetFrom() string {
@@ -274,7 +404,7 @@
 func (x *RspFile) Reset() {
 	*x = RspFile{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_sbox_proto_msgTypes[3]
+		mi := &file_sbox_proto_msgTypes[4]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -287,7 +417,7 @@
 func (*RspFile) ProtoMessage() {}
 
 func (x *RspFile) ProtoReflect() protoreflect.Message {
-	mi := &file_sbox_proto_msgTypes[3]
+	mi := &file_sbox_proto_msgTypes[4]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -300,7 +430,7 @@
 
 // Deprecated: Use RspFile.ProtoReflect.Descriptor instead.
 func (*RspFile) Descriptor() ([]byte, []int) {
-	return file_sbox_proto_rawDescGZIP(), []int{3}
+	return file_sbox_proto_rawDescGZIP(), []int{4}
 }
 
 func (x *RspFile) GetFile() string {
@@ -330,7 +460,7 @@
 func (x *PathMapping) Reset() {
 	*x = PathMapping{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_sbox_proto_msgTypes[4]
+		mi := &file_sbox_proto_msgTypes[5]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -343,7 +473,7 @@
 func (*PathMapping) ProtoMessage() {}
 
 func (x *PathMapping) ProtoReflect() protoreflect.Message {
-	mi := &file_sbox_proto_msgTypes[4]
+	mi := &file_sbox_proto_msgTypes[5]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -356,7 +486,7 @@
 
 // Deprecated: Use PathMapping.ProtoReflect.Descriptor instead.
 func (*PathMapping) Descriptor() ([]byte, []int) {
-	return file_sbox_proto_rawDescGZIP(), []int{4}
+	return file_sbox_proto_rawDescGZIP(), []int{5}
 }
 
 func (x *PathMapping) GetFrom() string {
@@ -383,7 +513,7 @@
 	0x08, 0x63, 0x6f, 0x6d, 0x6d, 0x61, 0x6e, 0x64, 0x73, 0x12, 0x25, 0x0a, 0x0e, 0x6f, 0x75, 0x74,
 	0x70, 0x75, 0x74, 0x5f, 0x64, 0x65, 0x70, 0x66, 0x69, 0x6c, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28,
 	0x09, 0x52, 0x0d, 0x6f, 0x75, 0x74, 0x70, 0x75, 0x74, 0x44, 0x65, 0x70, 0x66, 0x69, 0x6c, 0x65,
-	0x22, 0xdc, 0x01, 0x0a, 0x07, 0x43, 0x6f, 0x6d, 0x6d, 0x61, 0x6e, 0x64, 0x12, 0x2b, 0x0a, 0x0b,
+	0x22, 0xb3, 0x02, 0x0a, 0x07, 0x43, 0x6f, 0x6d, 0x6d, 0x61, 0x6e, 0x64, 0x12, 0x2b, 0x0a, 0x0b,
 	0x63, 0x6f, 0x70, 0x79, 0x5f, 0x62, 0x65, 0x66, 0x6f, 0x72, 0x65, 0x18, 0x01, 0x20, 0x03, 0x28,
 	0x0b, 0x32, 0x0a, 0x2e, 0x73, 0x62, 0x6f, 0x78, 0x2e, 0x43, 0x6f, 0x70, 0x79, 0x52, 0x0a, 0x63,
 	0x6f, 0x70, 0x79, 0x42, 0x65, 0x66, 0x6f, 0x72, 0x65, 0x12, 0x14, 0x0a, 0x05, 0x63, 0x68, 0x64,
@@ -396,23 +526,37 @@
 	0x73, 0x68, 0x18, 0x05, 0x20, 0x01, 0x28, 0x09, 0x52, 0x09, 0x69, 0x6e, 0x70, 0x75, 0x74, 0x48,
 	0x61, 0x73, 0x68, 0x12, 0x2a, 0x0a, 0x09, 0x72, 0x73, 0x70, 0x5f, 0x66, 0x69, 0x6c, 0x65, 0x73,
 	0x18, 0x06, 0x20, 0x03, 0x28, 0x0b, 0x32, 0x0d, 0x2e, 0x73, 0x62, 0x6f, 0x78, 0x2e, 0x52, 0x73,
-	0x70, 0x46, 0x69, 0x6c, 0x65, 0x52, 0x08, 0x72, 0x73, 0x70, 0x46, 0x69, 0x6c, 0x65, 0x73, 0x22,
-	0x4a, 0x0a, 0x04, 0x43, 0x6f, 0x70, 0x79, 0x12, 0x12, 0x0a, 0x04, 0x66, 0x72, 0x6f, 0x6d, 0x18,
-	0x01, 0x20, 0x02, 0x28, 0x09, 0x52, 0x04, 0x66, 0x72, 0x6f, 0x6d, 0x12, 0x0e, 0x0a, 0x02, 0x74,
-	0x6f, 0x18, 0x02, 0x20, 0x02, 0x28, 0x09, 0x52, 0x02, 0x74, 0x6f, 0x12, 0x1e, 0x0a, 0x0a, 0x65,
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+	0x18, 0x01, 0x20, 0x02, 0x28, 0x09, 0x52, 0x04, 0x66, 0x72, 0x6f, 0x6d, 0x12, 0x0e, 0x0a, 0x02,
+	0x74, 0x6f, 0x18, 0x02, 0x20, 0x02, 0x28, 0x09, 0x52, 0x02, 0x74, 0x6f, 0x42, 0x23, 0x5a, 0x21,
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+	0x6f,
 }
 
 var (
@@ -427,25 +571,27 @@
 	return file_sbox_proto_rawDescData
 }
 
-var file_sbox_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
+var file_sbox_proto_msgTypes = make([]protoimpl.MessageInfo, 6)
 var file_sbox_proto_goTypes = []interface{}{
-	(*Manifest)(nil),    // 0: sbox.Manifest
-	(*Command)(nil),     // 1: sbox.Command
-	(*Copy)(nil),        // 2: sbox.Copy
-	(*RspFile)(nil),     // 3: sbox.RspFile
-	(*PathMapping)(nil), // 4: sbox.PathMapping
+	(*Manifest)(nil),            // 0: sbox.Manifest
+	(*Command)(nil),             // 1: sbox.Command
+	(*EnvironmentVariable)(nil), // 2: sbox.EnvironmentVariable
+	(*Copy)(nil),                // 3: sbox.Copy
+	(*RspFile)(nil),             // 4: sbox.RspFile
+	(*PathMapping)(nil),         // 5: sbox.PathMapping
 }
 var file_sbox_proto_depIdxs = []int32{
 	1, // 0: sbox.Manifest.commands:type_name -> sbox.Command
-	2, // 1: sbox.Command.copy_before:type_name -> sbox.Copy
-	2, // 2: sbox.Command.copy_after:type_name -> sbox.Copy
-	3, // 3: sbox.Command.rsp_files:type_name -> sbox.RspFile
-	4, // 4: sbox.RspFile.path_mappings:type_name -> sbox.PathMapping
-	5, // [5:5] is the sub-list for method output_type
-	5, // [5:5] is the sub-list for method input_type
-	5, // [5:5] is the sub-list for extension type_name
-	5, // [5:5] is the sub-list for extension extendee
-	0, // [0:5] is the sub-list for field type_name
+	3, // 1: sbox.Command.copy_before:type_name -> sbox.Copy
+	3, // 2: sbox.Command.copy_after:type_name -> sbox.Copy
+	4, // 3: sbox.Command.rsp_files:type_name -> sbox.RspFile
+	2, // 4: sbox.Command.env:type_name -> sbox.EnvironmentVariable
+	5, // 5: sbox.RspFile.path_mappings:type_name -> sbox.PathMapping
+	6, // [6:6] is the sub-list for method output_type
+	6, // [6:6] is the sub-list for method input_type
+	6, // [6:6] is the sub-list for extension type_name
+	6, // [6:6] is the sub-list for extension extendee
+	0, // [0:6] is the sub-list for field type_name
 }
 
 func init() { file_sbox_proto_init() }
@@ -479,7 +625,7 @@
 			}
 		}
 		file_sbox_proto_msgTypes[2].Exporter = func(v interface{}, i int) interface{} {
-			switch v := v.(*Copy); i {
+			switch v := v.(*EnvironmentVariable); i {
 			case 0:
 				return &v.state
 			case 1:
@@ -491,7 +637,7 @@
 			}
 		}
 		file_sbox_proto_msgTypes[3].Exporter = func(v interface{}, i int) interface{} {
-			switch v := v.(*RspFile); i {
+			switch v := v.(*Copy); i {
 			case 0:
 				return &v.state
 			case 1:
@@ -503,6 +649,18 @@
 			}
 		}
 		file_sbox_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*RspFile); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_sbox_proto_msgTypes[5].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*PathMapping); i {
 			case 0:
 				return &v.state
@@ -515,13 +673,18 @@
 			}
 		}
 	}
+	file_sbox_proto_msgTypes[2].OneofWrappers = []interface{}{
+		(*EnvironmentVariable_Value)(nil),
+		(*EnvironmentVariable_Unset)(nil),
+		(*EnvironmentVariable_Inherit)(nil),
+	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_sbox_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   5,
+			NumMessages:   6,
 			NumExtensions: 0,
 			NumServices:   0,
 		},
diff --git a/cmd/sbox/sbox_proto/sbox.proto b/cmd/sbox/sbox_proto/sbox.proto
index 2f0dcf0..1158554 100644
--- a/cmd/sbox/sbox_proto/sbox.proto
+++ b/cmd/sbox/sbox_proto/sbox.proto
@@ -51,6 +51,30 @@
   // A list of files that will be copied before the sandboxed command, and whose contents should be
   // copied as if they were listed in copy_before.
   repeated RspFile rsp_files = 6;
+
+  // The environment variables that will be set or unset while running the command.
+  // Also see dont_inherit_env.
+  repeated EnvironmentVariable env = 7;
+
+  // By default, all environment variables are inherited from the calling process, but may be
+  // replaced or unset by env. If dont_inherit_env is set, no environment variables will be
+  // inherited, and instead only the variables in env will be defined.
+  optional bool dont_inherit_env = 8;
+}
+
+message EnvironmentVariable {
+  // The name of the environment variable
+  required string name = 1;
+  oneof state {
+    // The value to set the environment variable to.
+    string value = 2;
+    // This environment variable should be unset in the command.
+    bool unset = 3;
+    // This environment variable should be inherited from the parent process.
+    // Can be combined with dont_inherit_env to only inherit certain environment
+    // variables.
+    bool inherit = 4;
+  }
 }
 
 // Copy describes a from-to pair of files to copy.  The paths may be relative, the root that they