 <p>You can use <code>BindingUtils</code> to get notified when the <code>dataProvider</code> property of the combo box changes:</p> <pre><code>BindingUtils.bindSetter(comboBoxDataProviderChanged, comboBox, "dataProvider"); </code></pre> <p><code>BindingUtils</code> lives in the <code>mx.binding.utils</code> package.</p> <p>I have a longer description of how to work with <code>BindingUtils</code> here: <a href="http://stackoverflow.com/questions/14247/flex-does-painless-programmatic-data-binding-exist#14261">Does painless programmatic data binding exist?</a></p>