All good freelancers who have worked for over a year should be able to provide you with at least one reference. References, whether you actually contact them or not, can offer reassurance that the freelancer is a worthwhile investment. If you do contact the freelancer's references, you can also ask questions about what it was like to work with the freelancer. This will offer yet another perspective on whether or not the freelancer is a good fit for your project and your personal working style.