Speededness refers to the situation where the time limits on a standardized test do not allow substantial numbers of examinees to fully consider all test items. When tests are not intended to measure speed of responding, speededness introduces a severe threat to the validity of interpretations based on test scores. In this article, we describe test speededness, its potential threats to validity, and traditional and modern methods that can be used to assess the presence of speededness. We argue that more attention must be paid to this issue and that more research must be done to set appropriate time limits on power tests so that speed of responding does not interfere with the construct measured.