Media reports have recently given significant attention to the opt-out movement, an organized effort to refuse to take standardized tests. Although the narrative often told in early press accounts was of a viral grass-roots effort led by parents who object to state-mandated testing, the reality has turned out to be more complicated. Through a synthesis of news accounts, research studies, survey results, and state and federal education department documents, this paper examines the opt-out movement and some of the dynamics that appear to underlie it. Several topics are covered, including the movement's extent, the demographics of those participating in it, how much time students devote to tests, what other factors might be motivating the movement, and the level of public support for testing in general. The paper concludes with suggestions for how the assessment community might respond to the concerns raised by the movement and by the general public.