diff --git a/components/script/dom/htmlformelement.rs b/components/script/dom/htmlformelement.rs
index 53867c755f82..dfd2dac46506 100755
--- a/components/script/dom/htmlformelement.rs
+++ b/components/script/dom/htmlformelement.rs
@@ -7,6 +7,7 @@ use dom::bindings::codegen::Bindings::BlobBinding::BlobMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use dom::bindings::codegen::Bindings::HTMLButtonElementBinding::HTMLButtonElementMethods;
+use dom::bindings::codegen::Bindings::HTMLElementBinding::HTMLElementBinding::HTMLElementMethods;
 use dom::bindings::codegen::Bindings::HTMLFormControlsCollectionBinding::HTMLFormControlsCollectionMethods;
 use dom::bindings::codegen::Bindings::HTMLFormElementBinding;
 use dom::bindings::codegen::Bindings::HTMLFormElementBinding::HTMLFormElementMethods;
@@ -454,13 +455,18 @@ impl HTMLFormElement {
     /// Interactively validate the constraints of form elements
     /// https://html.spec.whatwg.org/multipage/#interactively-validate-the-constraints
     fn interactive_validation(&self) -> Result<(), ()> {
-        // Step 1-3
-        let _unhandled_invalid_controls = match self.static_validation() {
+        // Step 1-2
+        let unhandled_invalid_controls = match self.static_validation() {
             Ok(()) => return Ok(()),
             Err(err) => err
         };
-        // TODO: Report the problems with the constraints of at least one of
-        //       the elements given in unhandled invalid controls to the user
+        // Step 3
+        // TODO: Replace println! by something more visible to the user when a better reporting method
+        // becomes available.
+        let ref first_invalid_element = unhandled_invalid_controls[0].as_html_element();
+        println!("Validation error in element {}",
+                 first_invalid_element.upcast::<Element>().get_string_attribute(&local_name!("name")));
+        first_invalid_element.Focus();
         // Step 4
         Err(())
     }
@@ -757,6 +763,16 @@ impl FormSubmittableElement {
             unreachable!()
         }
     }
+
+    fn as_html_element(&self) -> &HTMLElement {
+        match *self {
+            FormSubmittableElement::ButtonElement(ref button) => button.upcast(),
+            FormSubmittableElement::InputElement(ref input) => input.upcast(),
+            FormSubmittableElement::ObjectElement(ref object) => object.upcast(),
+            FormSubmittableElement::SelectElement(ref select) => select.upcast(),
+            FormSubmittableElement::TextAreaElement(ref textarea) => textarea.upcast()
+        }
+    }
 }
 
 #[derive(Copy, Clone, HeapSizeOf)]
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index fc20326b906e..92ac2121cb97 100755
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use caseless::compatibility_caseless_match_str;
+use core::borrow::Borrow;
 use dom::activation::{Activatable, ActivationSource, synthetic_click_activation};
 use dom::attr::Attr;
 use dom::bindings::cell::DOMRefCell;
@@ -43,11 +44,13 @@ use mime_guess;
 use net_traits::{CoreResourceMsg, IpcSend};
 use net_traits::blob_url_store::get_blob_origin;
 use net_traits::filemanager_thread::{FileManagerThreadMsg, FilterPattern};
+use regex::Regex;
 use script_layout_interface::rpc::TextIndexResponse;
 use script_traits::ScriptMsg as ConstellationMsg;
 use servo_atoms::Atom;
 use std::borrow::ToOwned;
 use std::cell::Cell;
+use std::error::{Error as StdError};
 use std::ops::Range;
 use style::attr::AttrValue;
 use style::element_state::*;
@@ -1188,7 +1191,63 @@ impl Validatable for HTMLInputElement {
         true
     }
     fn validate(&self, _validate_flags: ValidationFlags) -> bool {
-        // call stub methods defined in validityState.rs file here according to the flags set in validate_flags
+        use dom::validitystate::*;
+
+        let value = self.Value();
+        let value_str: &str = value.borrow();
+        // https://html.spec.whatwg.org/multipage/#suffering-from-being-missing
+        if _validate_flags.contains(VALUE_MISSING) {
+            if value_str.is_empty() {
+                return false;
+            }
+        }
+        // https://html.spec.whatwg.org/multipage/#suffering-from-a-type-mismatch
+        if _validate_flags.contains(TYPE_MISMATCH) {
+            let validation_patterns = match self.Type().borrow() {
+                "url" => vec!(".", "/"),
+                "email" => vec!("@"),
+                _ => vec!(),
+            };
+
+            if validation_patterns.iter().all(|&p| !value_str.contains(p)) {
+                return false;
+            }
+        }
+        // https://html.spec.whatwg.org/multipage/#suffering-from-a-pattern-mismatch
+        if _validate_flags.contains(PATTERN_MISMATCH) {
+            let pattern = self.Pattern();
+            let pattern_str: &str = pattern.borrow();
+            if pattern_str.len() > 0 {
+                let pattern_regex = format!("^{}$", pattern_str);
+                match Regex::new(pattern_regex.as_str()) {
+                    Ok(regex) => {
+                        if !regex.is_match(value_str) {
+                            return false;
+                        }
+                    },
+                    Err(error) => {
+                        // TODO When possible, report this error to the developer console, as suggested in
+                        // https://html.spec.whatwg.org/multipage/#attr-input-pattern
+                        println!("Invalid pattern for element {}: {}",
+                                 self.Name(), error.description());
+                    }
+                };
+            }
+        }
+        // https://html.spec.whatwg.org/multipage/#suffering-from-being-too-long
+        if _validate_flags.contains(TOO_LONG) {
+            let maxlength = self.maxlength.get();
+            if maxlength != DEFAULT_MAX_LENGTH && value_str.len() > (maxlength as usize) {
+                return false;
+            }
+        }
+        // https://html.spec.whatwg.org/multipage/#suffering-from-being-too-short
+        if _validate_flags.contains(TOO_SHORT) {
+            let minlength = self.minlength.get();
+            if minlength != DEFAULT_MIN_LENGTH && value_str.len() < (minlength as usize) {
+                return false;
+            }
+        }
         true
     }
 }
diff --git a/components/script/dom/validitystate.rs b/components/script/dom/validitystate.rs
index 879438aa3893..8db74131aac9 100755
--- a/components/script/dom/validitystate.rs
+++ b/components/script/dom/validitystate.rs
@@ -70,56 +70,56 @@ impl ValidityState {
 impl ValidityStateMethods for ValidityState {
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-valuemissing
     fn ValueMissing(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(VALUE_MISSING))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-typemismatch
     fn TypeMismatch(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(TYPE_MISMATCH))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-patternmismatch
     fn PatternMismatch(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(PATTERN_MISMATCH))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-toolong
     fn TooLong(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(TOO_LONG))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-tooshort
     fn TooShort(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(TOO_SHORT))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-rangeunderflow
     fn RangeUnderflow(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(RANGE_UNDERFLOW))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-rangeoverflow
     fn RangeOverflow(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(RANGE_OVERFLOW))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-stepmismatch
     fn StepMismatch(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(STEP_MISMATCH))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-badinput
     fn BadInput(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(BAD_INPUT))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-customerror
     fn CustomError(&self) -> bool {
-        false
+        self.element.as_maybe_validatable().map_or(false, |e| e.validate(CUSTOM_ERROR))
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-validitystate-valid
     fn Valid(&self) -> bool {
-        false
+        !self.element.as_maybe_validatable().map_or(false, |e| e.validate(ValidationFlags::all()))
     }
 }