If you included Section 508 Acceptance Criteria in your solicitation, you need to evaluate the products delivered using your acceptance criteria.
Tools, Guidance, and Resources
A BuyAccessible Wizard session will produce an Acceptance Guide tailored for that product. The Acceptance Guide includes a list of provisions that are relevant as well as the answer to the question, "How can I tell if this requirement is met?"(The Wizard also gives you a GPAT to include in your solicitation, as well as an Evaluation Guide that helps you assess responses to the GPAT.)
Quick Reference Guide
When Section 508 law first came into effect, GSA facilitated the Accessibility Forum. Over 960 individuals from more than 600 companies, associations for people with disabilities, research and standards institutes, and government agencies from throughout the US and Canada registered interest and contributed in the work of the Forum. One of the documents that came out of the Forum was the Quick Reference Guide, which lists every Section 508 provision, defines terms, explains the provision, and answers, "How can I tell if this provision is met?"
Federal CrowdSource Mobile Testing Program
Learn about this free service provided for federal agencies by federal employees. They do compatibility testing, determining how mobile websites display on the multiple makes and models of devices, operating systems, and mobile browsers.