The study aims at developing and exploring a novel video-based assessment that captures classroom management expertise (CME) of teachers and for which statistical results are provided. CME measurement is conceptualized by using four video clips that refer to typical classroom management situations in which teachers are heavily challenged (involving the challenges to manage transitions, instructional time, student behavior, and instructional feedback) and by applying three cognitive demands posed on respondents when responding to test items related to the video clips (accuracy of perception, holistic perception, and justification of action). Research questions are raised regarding reliability, testlet effects (related to the four video clips applied for measurement), intercorrelations of cognitive demands, and criterion-related validity of the instrument. Evidence is provided that (1) using a video-based assessment CME can be measured in a reliable way, (2) the CME total score represents a general ability that is only slightly influenced by testlet effects related to the four video clips, (3) the three cognitive demands conceptualized for the measurement of CME are highly intercorrelated, and (4) the CME measure is positively correlated with declarative-conceptual general pedagogical knowledge (medium effect size), whereas it shows only small size correlations with non-cognitive teacher variables.