How to rename address labels on Address field module?
This can be done with hook_form_alter:

function MY_MODULE_form_alter(&amp;$form, &amp;$form_state, $form_id) {

    //drupal_set_message("Form ID is : " . $form_id);

    switch($form_id) {

        case 'MY_FORM_ID':

            // dpm($form);

            // $form['NAME_OF_YOUR_FIELD'] - this is the field you want to edit

            // check that the field is set before looping over values
            if(isset($form['NAME_OF_YOUR_FIELD'][LANGUAGE_NONE])) {
                // loop over each values passing $item by reference
                foreach($form['NAME_OF_YOUR_FIELD'][LANGUAGE_NONE] as &amp;$item) {
                    if(is_array($item) &amp;&amp; isset($item['street_block'])) {
                        $item['street_block']['thoroughfare']['#title'] = 'Address Line 1';
                        $item['street_block']['premise']['#title'] = 'Address Line 2';
                    }
                }
            }
            break;
    }

}


I found the path to the variable I wanted to change by outputting the $form array to the message area using devel's dpm function, and then searching though the array for the value "Address 1" using the search krumo module.