diff --git a/cmd/dagger/cmd/up.go b/cmd/dagger/cmd/up.go
index 721f8af1..925bf248 100644
--- a/cmd/dagger/cmd/up.go
+++ b/cmd/dagger/cmd/up.go
@@ -142,7 +142,11 @@ func checkUniverseVersion(ctx context.Context, projectPath string) bool {
 func europaUp(ctx context.Context, cl *client.Client, args ...string) error {
 	lg := log.Ctx(ctx)
 
-	p, err := plan.Load(ctx, args...)
+	p, err := plan.Load(ctx, plan.Config{
+		Args: args,
+		With: viper.GetStringSlice("with"),
+	})
+
 	if err != nil {
 		lg.Fatal().Err(err).Msg("failed to load plan")
 	}
@@ -220,6 +224,7 @@ func checkInputs(ctx context.Context, env *environment.Environment) error {
 func init() {
 	upCmd.Flags().BoolP("force", "f", false, "Force up, disable inputs check")
 	upCmd.Flags().String("output", "", "Write computed output. Prints on stdout if set to-")
+	upCmd.Flags().StringArrayP("with", "w", []string{}, "")
 
 	if err := viper.BindPFlags(upCmd.Flags()); err != nil {
 		panic(err)
diff --git a/plan/plan.go b/plan/plan.go
index 659b79d6..08346821 100644
--- a/plan/plan.go
+++ b/plan/plan.go
@@ -19,24 +19,46 @@ import (
 )
 
 type Plan struct {
+	config Config
+
 	context *plancontext.Context
 	source  *compiler.Value
 }
 
-func Load(ctx context.Context, args ...string) (*Plan, error) {
-	log.Ctx(ctx).Debug().Interface("args", args).Msg("loading plan")
+type Config struct {
+	Args []string
+	With []string
+}
+
+func Load(ctx context.Context, cfg Config) (*Plan, error) {
+	log.Ctx(ctx).Debug().Interface("args", cfg.Args).Msg("loading plan")
 
 	// FIXME: universe vendoring
 	if err := state.VendorUniverse(ctx, ""); err != nil {
 		return nil, err
 	}
 
-	v, err := compiler.Build("", nil, args...)
+	v, err := compiler.Build("", nil, cfg.Args...)
 	if err != nil {
 		return nil, err
 	}
 
+	for i, param := range cfg.With {
+		log.Ctx(ctx).Debug().Interface("with", param).Msg("compiling overlay")
+		paramV, err := compiler.Compile(fmt.Sprintf("with%v", i), param)
+		if err != nil {
+			return nil, err
+		}
+
+		log.Ctx(ctx).Debug().Interface("with", param).Msg("filling overlay")
+		fillErr := v.FillPath(cue.MakePath(), paramV)
+		if fillErr != nil {
+			return nil, fillErr
+		}
+	}
+
 	p := &Plan{
+		config:  cfg,
 		context: plancontext.New(),
 		source:  v,
 	}
diff --git a/stdlib/europa/dagger/engine/plan.cue b/stdlib/europa/dagger/engine/plan.cue
index 29b2efaf..20ebce6a 100644
--- a/stdlib/europa/dagger/engine/plan.cue
+++ b/stdlib/europa/dagger/engine/plan.cue
@@ -12,10 +12,7 @@ package engine
 		// Securely receive secrets
 		secrets: [name=string]: _#inputSecret
 		// Receive runtime parameters
-		params: {
-			@dagger(notimplemented)
-			[name=string]: _
-		}
+		params: [name=string]: _
 	}
 
 	// Send outputs to the client
diff --git a/tests/plan.bats b/tests/plan.bats
index 51ee02c7..f6aaaec0 100644
--- a/tests/plan.bats
+++ b/tests/plan.bats
@@ -82,6 +82,20 @@ setup() {
 	assert_output --partial 'failed: exec: "rtyet": executable file not found'
 }
 
+@test "plan/with" {
+  cd "$TESTDIR"
+  "$DAGGER" --europa up --with 'inputs: params: foo:"bar"' ./plan/with/params.cue
+  "$DAGGER" --europa up --with 'actions: verify: env: FOO: "bar"' ./plan/with/actions.cue
+  
+  run "$DAGGER" --europa up --with 'inputs: params: foo:1' ./plan/with/params.cue
+  assert_failure
+  assert_output --partial "conflicting values string and 1"
+  
+  run "$DAGGER" --europa up ./plan/with/params.cue
+  assert_failure
+  assert_output --partial "actions.verify.env.FOO: non-concrete value string"
+}
+
 @test "plan/outputs" {
     cd "$TESTDIR"/plan/outputs
 
diff --git a/tests/plan/with/actions.cue b/tests/plan/with/actions.cue
new file mode 100644
index 00000000..1d856fdd
--- /dev/null
+++ b/tests/plan/with/actions.cue
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"alpha.dagger.io/europa/dagger/engine"
+)
+
+engine.#Plan & {
+
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		verify: engine.#Exec & {
+			input: image.output
+			env: FOO: string
+			args: [
+				"sh", "-c",
+				#"""
+					test -n "$FOO"
+					"""#,
+			]
+		}
+	}
+}
diff --git a/tests/plan/with/params.cue b/tests/plan/with/params.cue
new file mode 100644
index 00000000..402ac379
--- /dev/null
+++ b/tests/plan/with/params.cue
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"alpha.dagger.io/europa/dagger/engine"
+)
+
+engine.#Plan & {
+	inputs: params: foo: string
+
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		verify: engine.#Exec & {
+			input: image.output
+			env: FOO: inputs.params.foo
+			args: [
+				"sh", "-c",
+				#"""
+					test "$FOO" = "bar"
+					"""#,
+			]
+		}
+	}
+}