Constructed-response tasks have captured the attention of testers and educators for some time (e.g., Cureton, 1951), because they present goal-oriented, contextualized challenges that prompt examinees to deploy cognitive skills and domain-related knowledge in authentic performances. Such performances present a distinct advantage when teaching, learning, and assessment focus on what learners can do rather than merely emphasizing what they know (Wiggins, 1998). Over the past several decades, communicative performance tasks have come to play a crucial role in language assessments on a variety of levels, from classroom-based tests, to professional certifications, to large-scale language proficiency exams (Norris, 2009, 2016). However, the use of such tasks for assessment purposes remains contentious, and numerous language testing alternatives are available at potentially lower cost and degree of effort. In order to facilitate decisions about when and why to adopt task-based designs for language assessment, I first outline the relationship between assessment designs and their intended uses and consequences. I then introduce two high-stakes examples of language assessment circumstances (job certification and admissions testing) that suggest a need for task-based designs, and I review the corresponding fit of several assessments currently in use for these purposes. In relation to these purposes, I also suggest some of the positive consequences of task-based designs for language learners, teachers, and society, and I point to the dangers of using assessments that do not incorporate communicative tasks or do so inappropriately. I conclude by highlighting other circumstances that call for task-based designs, and I suggest how advances in technology may help to address associated challenges.