diff --git a/.changes/unreleased/ENHANCEMENTS-20240815-135108.yaml b/.changes/unreleased/ENHANCEMENTS-20240815-135108.yaml
new file mode 100644
index 00000000..9c6cb773
--- /dev/null
+++ b/.changes/unreleased/ENHANCEMENTS-20240815-135108.yaml
@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: Validate Stack and Deployment files for unreferenced origins
+time: 2024-08-15T13:51:08.906805-04:00
+custom:
+    Issue: "1797"
+    Repository: terraform-ls
diff --git a/internal/features/stacks/decoder/validations/unreferenced_origins.go b/internal/features/stacks/decoder/validations/unreferenced_origins.go
new file mode 100644
index 00000000..593b2dc3
--- /dev/null
+++ b/internal/features/stacks/decoder/validations/unreferenced_origins.go
@@ -0,0 +1,81 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validations
+
+import (
+	"context"
+	"fmt"
+	"slices"
+
+	"github.com/hashicorp/hcl-lang/decoder"
+	"github.com/hashicorp/hcl-lang/lang"
+	"github.com/hashicorp/hcl-lang/reference"
+	"github.com/hashicorp/hcl/v2"
+)
+
+func UnreferencedOrigins(ctx context.Context, pathCtx *decoder.PathContext) lang.DiagnosticsMap {
+	diagsMap := make(lang.DiagnosticsMap)
+
+	for _, origin := range pathCtx.ReferenceOrigins {
+		localOrigin, ok := origin.(reference.LocalOrigin)
+		if !ok {
+			// We avoid reporting on other origin types.
+			//
+			// DirectOrigin is represented as module's source
+			// and we already validate existence of the local module
+			// and avoiding linking to a non-existent module in terraform-schema
+			// https://github.com/hashicorp/terraform-schema/blob/b39f3de0/schema/module_schema.go#L212-L232
+			//
+			// PathOrigin is represented as module inputs
+			// and we can validate module inputs more meaningfully
+			// as attributes in body (module block), e.g. raise that
+			// an input is required or unknown, rather than "reference"
+			// lacking a corresponding target.
+			continue
+		}
+
+		address := localOrigin.Address()
+
+		if len(address) > 2 {
+			// We temporarily ignore references with more than 2 segments
+			// as these indicate references to complex types
+			// which we do not fully support yet.
+			// TODO: revisit as part of https://github.com/hashicorp/terraform-ls/issues/653
+
+			// However, we still want to validate references to component provider and identity_token
+			// for Stacks. This is relatively safe as we know the structure of the references
+			// and can validate them without needing to know the schema of the referenced object.
+			// TODO: revisit after user feedback
+			supported := []string{"provider", "identity_token"}
+			if !slices.Contains(supported, address[0].String()) {
+				continue
+			}
+		}
+
+		// we only initially validate variables, providers, and identity_tokens
+		// resources can have unknown schema and will be researched at a later point
+		// TODO: revisit as part of https://github.com/hashicorp/terraform-ls/issues/1364
+		supported := []string{"var", "provider", "identity_token"}
+		firstStep := address[0].String()
+		if !slices.Contains(supported, firstStep) {
+			continue
+		}
+
+		_, ok = pathCtx.ReferenceTargets.Match(localOrigin)
+		if !ok {
+			// target not found
+			fileName := origin.OriginRange().Filename
+			d := &hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  fmt.Sprintf("No declaration found for %q", address),
+				Subject:  origin.OriginRange().Ptr(),
+			}
+			diagsMap[fileName] = diagsMap[fileName].Append(d)
+
+			continue
+		}
+	}
+
+	return diagsMap
+}
diff --git a/internal/features/stacks/events.go b/internal/features/stacks/events.go
index f7a614cd..e8aabd51 100644
--- a/internal/features/stacks/events.go
+++ b/internal/features/stacks/events.go
@@ -289,6 +289,20 @@ func (f *StacksFeature) decodeStack(ctx context.Context, dir document.DirHandle,
 				}
 			}
 
+			_, err = f.stateStore.JobStore.EnqueueJob(ctx, job.Job{
+				Dir: dir,
+				Func: func(ctx context.Context) error {
+
+					return jobs.ReferenceValidation(ctx, f.store, f.moduleFeature, dir.Path())
+				},
+				Type:        operation.OpTypeReferenceStackValidation.String(),
+				DependsOn:   job.IDs{refOriginsId, refTargetsId},
+				IgnoreState: ignoreState,
+			})
+			if err != nil {
+				return deferIds, err
+			}
+
 			return deferIds, nil
 		},
 	})
diff --git a/internal/features/stacks/jobs/validation.go b/internal/features/stacks/jobs/validation.go
index 97522627..505f98a5 100644
--- a/internal/features/stacks/jobs/validation.go
+++ b/internal/features/stacks/jobs/validation.go
@@ -15,6 +15,7 @@ import (
 	"github.com/hashicorp/terraform-ls/internal/document"
 	"github.com/hashicorp/terraform-ls/internal/features/stacks/ast"
 	stackDecoder "github.com/hashicorp/terraform-ls/internal/features/stacks/decoder"
+	"github.com/hashicorp/terraform-ls/internal/features/stacks/decoder/validations"
 	"github.com/hashicorp/terraform-ls/internal/features/stacks/state"
 	"github.com/hashicorp/terraform-ls/internal/job"
 	ilsp "github.com/hashicorp/terraform-ls/internal/lsp"
@@ -116,3 +117,53 @@ func SchemaStackValidation(ctx context.Context, stackStore *state.StackStore, mo
 
 	return rErr
 }
+
+// ReferenceValidation does validation based on (mis)matched
+// reference origins and targets, to flag up "orphaned" references.
+//
+// It relies on [DecodeReferenceTargets] and [DecodeReferenceOrigins]
+// to supply both origins and targets to compare.
+func ReferenceValidation(ctx context.Context, stackStore *state.StackStore, moduleFeature stackDecoder.ModuleReader, stackPath string) error {
+	record, err := stackStore.StackRecordByPath(stackPath)
+	if err != nil {
+		return err
+	}
+
+	// Avoid validation if it is already in progress or already finished
+	if record.DiagnosticsState[globalAst.ReferenceValidationSource] != operation.OpStateUnknown && !job.IgnoreState(ctx) {
+		return job.StateNotChangedErr{Dir: document.DirHandleFromPath(stackPath)}
+	}
+
+	err = stackStore.SetDiagnosticsState(stackPath, globalAst.ReferenceValidationSource, operation.OpStateLoading)
+	if err != nil {
+		return err
+	}
+
+	pathReader := &stackDecoder.PathReader{
+		StateReader:  stackStore,
+		ModuleReader: moduleFeature,
+	}
+
+	stackDecoder, err := pathReader.PathContext(lang.Path{
+		Path:       stackPath,
+		LanguageID: ilsp.Stacks.String(),
+	})
+	if err != nil {
+		return err
+	}
+
+	deployDecoder, err := pathReader.PathContext(lang.Path{
+		Path:       stackPath,
+		LanguageID: ilsp.Deploy.String(),
+	})
+	if err != nil {
+		return err
+	}
+
+	diags := validations.UnreferencedOrigins(ctx, stackDecoder)
+
+	deployDiags := validations.UnreferencedOrigins(ctx, deployDecoder)
+	diags = diags.Extend(deployDiags)
+
+	return stackStore.UpdateDiagnostics(stackPath, globalAst.ReferenceValidationSource, ast.DiagnosticsFromMap(diags))
+}
diff --git a/internal/terraform/module/operation/op_type_string.go b/internal/terraform/module/operation/op_type_string.go
index b116ecb6..afa48295 100644
--- a/internal/terraform/module/operation/op_type_string.go
+++ b/internal/terraform/module/operation/op_type_string.go
@@ -27,15 +27,16 @@ func _() {
 	_ = x[OpTypeSchemaStackValidation-16]
 	_ = x[OpTypeSchemaVarsValidation-17]
 	_ = x[OpTypeReferenceValidation-18]
-	_ = x[OpTypeTerraformValidate-19]
-	_ = x[OpTypeParseStackConfiguration-20]
-	_ = x[OpTypeLoadStackMetadata-21]
-	_ = x[OpTypeLoadStackRequiredTerraformVersion-22]
+	_ = x[OpTypeReferenceStackValidation-19]
+	_ = x[OpTypeTerraformValidate-20]
+	_ = x[OpTypeParseStackConfiguration-21]
+	_ = x[OpTypeLoadStackMetadata-22]
+	_ = x[OpTypeLoadStackRequiredTerraformVersion-23]
 }
 
-const _OpType_name = "OpTypeUnknownOpTypeGetTerraformVersionOpTypeGetInstalledTerraformVersionOpTypeObtainSchemaOpTypeParseModuleConfigurationOpTypeParseVariablesOpTypeParseModuleManifestOpTypeLoadModuleMetadataOpTypeDecodeReferenceTargetsOpTypeDecodeReferenceOriginsOpTypeDecodeVarsReferencesOpTypeGetModuleDataFromRegistryOpTypeParseProviderVersionsOpTypePreloadEmbeddedSchemaOpTypeStacksPreloadEmbeddedSchemaOpTypeSchemaModuleValidationOpTypeSchemaStackValidationOpTypeSchemaVarsValidationOpTypeReferenceValidationOpTypeTerraformValidateOpTypeParseStackConfigurationOpTypeLoadStackMetadataOpTypeLoadStackRequiredTerraformVersion"
+const _OpType_name = "OpTypeUnknownOpTypeGetTerraformVersionOpTypeGetInstalledTerraformVersionOpTypeObtainSchemaOpTypeParseModuleConfigurationOpTypeParseVariablesOpTypeParseModuleManifestOpTypeLoadModuleMetadataOpTypeDecodeReferenceTargetsOpTypeDecodeReferenceOriginsOpTypeDecodeVarsReferencesOpTypeGetModuleDataFromRegistryOpTypeParseProviderVersionsOpTypePreloadEmbeddedSchemaOpTypeStacksPreloadEmbeddedSchemaOpTypeSchemaModuleValidationOpTypeSchemaStackValidationOpTypeSchemaVarsValidationOpTypeReferenceValidationOpTypeReferenceStackValidationOpTypeTerraformValidateOpTypeParseStackConfigurationOpTypeLoadStackMetadataOpTypeLoadStackRequiredTerraformVersion"
 
-var _OpType_index = [...]uint16{0, 13, 38, 72, 90, 120, 140, 165, 189, 217, 245, 271, 302, 329, 356, 389, 417, 444, 470, 495, 518, 547, 570, 609}
+var _OpType_index = [...]uint16{0, 13, 38, 72, 90, 120, 140, 165, 189, 217, 245, 271, 302, 329, 356, 389, 417, 444, 470, 495, 525, 548, 577, 600, 639}
 
 func (i OpType) String() string {
 	if i >= OpType(len(_OpType_index)-1) {
diff --git a/internal/terraform/module/operation/operation.go b/internal/terraform/module/operation/operation.go
index a4f1ed81..5d68ab96 100644
--- a/internal/terraform/module/operation/operation.go
+++ b/internal/terraform/module/operation/operation.go
@@ -36,6 +36,7 @@ const (
 	OpTypeSchemaStackValidation
 	OpTypeSchemaVarsValidation
 	OpTypeReferenceValidation
+	OpTypeReferenceStackValidation
 	OpTypeTerraformValidate
 	OpTypeParseStackConfiguration
 	OpTypeLoadStackMetadata