The extent to which a test's time limit alters a test taker's performance is known as speededness. The manifestation of speededness, or speeded behavior on a test, can be in the form of random guessing, leaving a substantial proportion of test items unanswered, or rushed test-taking behavior in general. Speeded responses do not depend solely on a test taker's ability and are therefore not appropriate for traditional item response theory. The literature on measuring the extent of speededness on a test is extensive and dates back over a half-century. Yet, simple rules of thumb for measuring speededness, dating back until at least Swineford in 1949, are still in operation—for example, 80% of the candidates reach the last item. The purpose of this research report is to provide a chronology and classification of methods for measuring speededness and to discuss ensuing research and development in measuring speededness.