diff --git a/command/test-fixtures/validate-invalid/missing_defined_var/main.tf b/command/test-fixtures/validate-invalid/missing_defined_var/main.tf
new file mode 100644
index 000000000..b3e122172
--- /dev/null
+++ b/command/test-fixtures/validate-invalid/missing_defined_var/main.tf
@@ -0,0 +1,10 @@
+resource "test_instance" "foo" {
+    ami = "bar"
+
+    network_interface {
+      device_index = 0
+      description = "Main network interface ${var.name}"
+    }
+}
+
+variable "name" {}
diff --git a/command/validate.go b/command/validate.go
index f693da244..c4be168af 100644
--- a/command/validate.go
+++ b/command/validate.go
@@ -1,12 +1,12 @@
 package command
 
 import (
-	"flag"
 	"fmt"
 	"path/filepath"
 	"strings"
 
 	"github.com/hashicorp/terraform/config"
+	"github.com/hashicorp/terraform/terraform"
 )
 
 // ValidateCommand is a Command implementation that validates the terraform files
@@ -17,15 +17,21 @@ type ValidateCommand struct {
 const defaultPath = "."
 
 func (c *ValidateCommand) Run(args []string) int {
-	args = c.Meta.process(args, false)
-	var dirPath string
+	args = c.Meta.process(args, true)
+	var checkVars bool
 
-	cmdFlags := flag.NewFlagSet("validate", flag.ContinueOnError)
-	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
+	cmdFlags := c.Meta.flagSet("validate")
+	cmdFlags.BoolVar(&checkVars, "check-variables", true, "check-variables")
+	cmdFlags.Usage = func() {
+		c.Ui.Error(c.Help())
+	}
 	if err := cmdFlags.Parse(args); err != nil {
 		return 1
 	}
 
+	args = cmdFlags.Args()
+
+	var dirPath string
 	if len(args) == 1 {
 		dirPath = args[0]
 	} else {
@@ -37,7 +43,7 @@ func (c *ValidateCommand) Run(args []string) int {
 			"Unable to locate directory %v\n", err.Error()))
 	}
 
-	rtnCode := c.validate(dir)
+	rtnCode := c.validate(dir, checkVars)
 
 	return rtnCode
 }
@@ -48,24 +54,38 @@ func (c *ValidateCommand) Synopsis() string {
 
 func (c *ValidateCommand) Help() string {
 	helpText := `
-Usage: terraform validate [options] [path]
+Usage: terraform validate [options] [dir]
 
-  Reads the Terraform files in the given path (directory) and
-  validates their syntax and basic semantics.
+  Validate the terraform files in a directory. Validation includes a
+  basic check of syntax as well as checking that all variables declared
+  in the configuration are specified in one of the possible ways:
 
-  This is not a full validation that is normally done with
-  a plan or apply operation, but can be used to verify the basic
-  syntax and usage of Terraform configurations is correct.
+      -var foo=...
+      -var-file=foo.vars
+      TF_VAR_foo environment variable
+      terraform.tfvars
+      default value
+
+  If dir is not specified, then the current directory will be used.
 
 Options:
 
-  -no-color           If specified, output won't contain any color.
+  -check-variables=true If set to true (default), the command will check
+                        whether all required variables have been specified.
 
+  -no-color             If specified, output won't contain any color.
+
+  -var 'foo=bar'        Set a variable in the Terraform configuration. This
+                        flag can be set multiple times.
+
+  -var-file=foo         Set variables in the Terraform configuration from
+                        a file. If "terraform.tfvars" is present, it will be
+                        automatically loaded if this flag is not specified.
 `
 	return strings.TrimSpace(helpText)
 }
 
-func (c *ValidateCommand) validate(dir string) int {
+func (c *ValidateCommand) validate(dir string, checkVars bool) int {
 	cfg, err := config.LoadDir(dir)
 	if err != nil {
 		c.Ui.Error(fmt.Sprintf(
@@ -78,5 +98,27 @@ func (c *ValidateCommand) validate(dir string) int {
 			"Error validating: %v\n", err.Error()))
 		return 1
 	}
+
+	if checkVars {
+		mod, err := c.Module(dir)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Failed to load root config module: %s", err))
+			return 1
+		}
+
+		opts := c.contextOpts()
+		opts.Module = mod
+
+		tfCtx, err := terraform.NewContext(opts)
+		if err != nil {
+			c.Ui.Error(fmt.Sprintf("Error: %v\n", err.Error()))
+			return 1
+		}
+
+		if !validateContext(tfCtx, c.Ui) {
+			return 1
+		}
+	}
+
 	return 0
 }
diff --git a/command/validate_test.go b/command/validate_test.go
index de293eed9..77bdfed97 100644
--- a/command/validate_test.go
+++ b/command/validate_test.go
@@ -7,21 +7,21 @@ import (
 	"github.com/mitchellh/cli"
 )
 
-func setupTest(fixturepath string) (*cli.MockUi, int) {
+func setupTest(fixturepath string, args ...string) (*cli.MockUi, int) {
 	ui := new(cli.MockUi)
 	c := &ValidateCommand{
 		Meta: Meta{
-			Ui: ui,
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
 		},
 	}
 
-	args := []string{
-		testFixturePath(fixturepath),
-	}
+	args = append(args, testFixturePath(fixturepath))
 
 	code := c.Run(args)
 	return ui, code
 }
+
 func TestValidateCommand(t *testing.T) {
 	if ui, code := setupTest("validate-valid"); code != 0 {
 		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
@@ -122,3 +122,21 @@ func TestWronglyUsedInterpolationShouldFail(t *testing.T) {
 		t.Fatalf("Should have failed: %d\n\n'%s'", code, ui.ErrorWriter.String())
 	}
 }
+
+func TestMissingDefinedVar(t *testing.T) {
+	ui, code := setupTest("validate-invalid/missing_defined_var")
+	if code != 1 {
+		t.Fatalf("Should have failed: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+
+	if !strings.Contains(ui.ErrorWriter.String(), "Required variable not set:") {
+		t.Fatalf("Should have failed: %d\n\n'%s'", code, ui.ErrorWriter.String())
+	}
+}
+
+func TestMissingDefinedVarConfigOnly(t *testing.T) {
+	ui, code := setupTest("validate-invalid/missing_defined_var", "-check-variables=false")
+	if code != 0 {
+		t.Fatalf("Should have passed: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+}
diff --git a/website/docs/commands/validate.html.markdown b/website/docs/commands/validate.html.markdown
index a13cc7e30..3a17c79af 100644
--- a/website/docs/commands/validate.html.markdown
+++ b/website/docs/commands/validate.html.markdown
@@ -24,10 +24,31 @@ The following can be reported:
  * invalid `module` name
  * interpolation used in places where it's unsupported
  	(e.g. `variable`, `depends_on`, `module.source`, `provider`)
+ * missing value for a variable (none of `-var foo=...` flag,
+   `-var-file=foo.vars` flag, `TF_VAR_foo` environment variable,
+   `terraform.tfvars`, or default value in the configuration)
 
 ## Usage
 
-Usage: `terraform validate [dir]`
+Usage: `terraform validate [options] [dir]`
 
 By default, `validate` requires no flags and looks in the current directory
-for the configurations.
\ No newline at end of file
+for the configurations.
+
+The command-line flags are all optional. The available flags are:
+
+* `-check-variables=true` - If set to true (default), the command will check
+  whether all required variables have been specified.
+
+* `-no-color` - Disables output with coloring.
+
+* `-var 'foo=bar'` - Set a variable in the Terraform configuration. This flag
+  can be set multiple times. Variable values are interpreted as
+  [HCL](/docs/configuration/syntax.html#HCL), so list and map values can be
+  specified via this flag.
+
+* `-var-file=foo` - Set variables in the Terraform configuration from
+   a [variable file](/docs/configuration/variables.html#variable-files). If
+  "terraform.tfvars" is present, it will be automatically loaded first. Any
+  files specified by `-var-file` override any values in a "terraform.tfvars".
+  This flag can be used multiple times.