In this article we show that differences between software providers in terms of productivity and quality can be very large and that traditional means of evaluating software providers, such as CVs and evaluations by reference clients, fail to separate the competent from the incompetent ones. We argue and motivate through analyses of empirical data that software clients would benefit from using work sample-based tests of software development providers' performance (trialsourcing) to guide their selection of providers. We discuss potential challenges of trialsourcing and provide recommendations on what to consider when designing proper trialsourcing processes.