David, as this is an older post, you probably already solved your problem, but I decided to write a PHP V3 API wrapper.   Check it out at https://packagist.org/packages/phpfui/constantcontact  You can also view the complete source code and documentation at http://phpfui.com/?n=PHPFUI%5CConstantContact.   It is a full implementation of the Constant Contact V3 API and updated nightly with any changes that are made to the YAML file.   If you need to do additional things, or need the latest API, it might make sense to take a look, rather than write it yourself. It also has a nice next() function to get paginated results.  Super easy to use.   Hope this helps. ... View more