diff --git a/package.json b/package.json
index 68ba823..5cbe8da 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,7 @@
   },
   "dependencies": {
     "axios": "^0.18.0",
+    "classnames": "^2.2.6",
     "date-fns": "^1.30.1",
     "lodash": "^4.17.11",
     "mobx": "^5.5.0",
diff --git a/src/css/_form.scss b/src/css/_form.scss
index 8d470dc..727184e 100644
--- a/src/css/_form.scss
+++ b/src/css/_form.scss
@@ -24,6 +24,16 @@
       color: #eee;
     }
 
+    &.has-error {
+      input, textarea {
+        border-color: #FB3A2F;
+      }
+    }
+
+    .form-error {
+      color: #FB3A2F;
+    }
+
     .input-group {
       position: relative;
       display: table;
diff --git a/src/js/components/Bubble.js b/src/js/components/Bubble.js
index 7316ac2..7996915 100644
--- a/src/js/components/Bubble.js
+++ b/src/js/components/Bubble.js
@@ -147,6 +147,7 @@ class Bubble extends Component {
       .createActivity(this.changesetWithDefaults)
       .then(() => {
         this.close()
+        this.changeset = {}
         this.formErrors = {}
       })
       .catch(this.handleSubmitError)
@@ -173,6 +174,7 @@ class Bubble extends Component {
         <Form
           projects={this.projects}
           changeset={this.changesetWithDefaults}
+          errors={this.formErrors}
           isLoading={this.isLoading}
           onChange={this.handleChange}
           onSubmit={this.handleSubmit}
diff --git a/src/js/components/Form.js b/src/js/components/Form.js
index fa52ac2..bfb3b97 100644
--- a/src/js/components/Form.js
+++ b/src/js/components/Form.js
@@ -1,6 +1,7 @@
 import React, { Component } from "react"
 import PropTypes from "prop-types"
 import Select from "components/Select"
+import cn from "classnames"
 
 class Form extends Component {
   static propTypes = {
@@ -10,6 +11,7 @@ class Form extends Component {
       task: PropTypes.object,
       hours: PropTypes.string
     }).isRequired,
+    errors: PropTypes.object,
     projects: PropTypes.array.isRequired,
     onChange: PropTypes.func.isRequired,
     onSubmit: PropTypes.func.isRequired
@@ -33,29 +35,39 @@ class Form extends Component {
       return null
     }
 
-    const { projects, changeset, onChange, onSubmit } = this.props
+    const { projects, changeset, errors, onChange, onSubmit } = this.props
     const project = Select.findOptionByValue(projects, changeset.assignment_id)
 
     return (
       <form onSubmit={onSubmit}>
-        <div className="form-group">
+        <div
+          className={cn("form-group", { "has-error": errors.assignment_id })}
+        >
           <Select
             name="assignment_id"
             options={projects}
             value={changeset.assignment_id}
+            hasError={!!errors.assignment_id}
             onChange={onChange}
           />
+          {errors.assignment_id ? (
+            <div className="form-error">{errors.assignment_id.join('; ')}</div>
+          ) : null}
         </div>
-        <div className="form-group">
+        <div className={cn("form-group", { "has-error": errors.task_id })}>
           <Select
             name="task_id"
             options={project?.tasks || []}
             value={changeset.task_id}
             onChange={onChange}
+            hasError={!!errors.task_id}
             noOptionsMessage={() => "Zuerst Projekt wählen"}
           />
+          {errors.task_id ? (
+            <div className="form-error">{errors.task_id.join('; ')}</div>
+          ) : null}
         </div>
-        <div className="form-group">
+        <div className={cn("form-group", { "has-error": errors.hours })}>
           <input
             name="hours"
             className="form-control"
@@ -65,8 +77,11 @@ class Form extends Component {
             autoComplete="off"
             autoFocus
           />
+          {errors.hours ? (
+            <div className="form-error">{errors.hours.join('; ')}</div>
+          ) : null}
         </div>
-        <div className="form-group">
+        <div className={cn("form-group", { "has-error": errors.description })}>
           <textarea
             name="description"
             onChange={onChange}
@@ -74,6 +89,9 @@ class Form extends Component {
             placeholder="Beschreibung der Tätigkeit - mind. 3 Zeichen"
             rows={4}
           />
+          {errors.description ? (
+            <div className="form-error">{errors.description.join('; ')}</div>
+          ) : null}
         </div>
 
         <button disabled={!this.isValid()}>Speichern</button>
diff --git a/src/js/components/Select.js b/src/js/components/Select.js
index 195c6fe..77678af 100644
--- a/src/js/components/Select.js
+++ b/src/js/components/Select.js
@@ -12,6 +12,7 @@ import {
   flatMap,
   pathEq
 } from "lodash/fp"
+import { trace } from "utils"
 
 const customTheme = theme => ({
   ...theme,
@@ -23,7 +24,11 @@ const customTheme = theme => ({
   }
 })
 
-const customStyles = {
+const customStyles = props => ({
+  control: (base, _state) => ({
+    ...base,
+    borderColor: props.hasError ? "#FB3A2F" : base.borderColor
+  }),
   groupHeading: (base, _state) => ({
     ...base,
     color: "black",
@@ -31,7 +36,7 @@ const customStyles = {
     fontWeight: "bold",
     fontSize: "100%"
   })
-}
+})
 
 const filterOption = createFilter({
   stringify: compose(
@@ -47,10 +52,10 @@ export default class Select extends Component {
     name: PropTypes.string.isRequired,
     value: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
     options: PropTypes.array,
+    hasError: PropTypes.bool,
     onChange: PropTypes.func.isRequired
   };
 
-
   static findOptionByValue = (selectOptions, value) => {
     const options = flatMap(
       option => (option.options ? option.options : option),
@@ -58,7 +63,7 @@ export default class Select extends Component {
     )
 
     return options.find(pathEq("value", value))
-  }
+  };
 
   handleChange = option => {
     const { name, onChange } = this.props
@@ -67,7 +72,7 @@ export default class Select extends Component {
   };
 
   render() {
-    const { value, ...passThroughProps } = this.props
+    const { value, hasError, ...passThroughProps } = this.props
     return (
       <ReactSelect
         {...passThroughProps}
@@ -75,7 +80,7 @@ export default class Select extends Component {
         onChange={this.handleChange}
         filterOption={filterOption}
         theme={customTheme}
-        styles={customStyles}
+        styles={customStyles(this.props)}
       />
     )
   }
diff --git a/yarn.lock b/yarn.lock
index 807073b..7d383b1 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1709,7 +1709,7 @@ class-utils@^0.3.5:
     isobject "^3.0.0"
     static-extend "^0.1.1"
 
-classnames@^2.2.5:
+classnames@^2.2.5, classnames@^2.2.6:
   version "2.2.6"
   resolved "https://registry.yarnpkg.com/classnames/-/classnames-2.2.6.tgz#43935bffdd291f326dad0a205309b38d00f650ce"
   integrity sha512-JR/iSQOSt+LQIWwrwEzJ9uk0xfN3mTVYMwt1Ir5mUcSN6pU+V4zQFFaJsclJbPuAUQH+yfWef6tm7l1quW3C8Q==