Contemporary education reforms focus on assessing teachers' performance and developing selection mechanisms for hiring effective teachers. Tools that enable the prediction of teachers' classroom performance promote schools' ability to hire teachers more likely to be successful in the classroom. In addition, these assessment tools can be used for teacher training and preparation that contributes to improved student performance. This article summarizes the theoretical and empirical support for a direct assessment of teachers' skill in detecting and identifying effective classroom interactions--the Video Assessment of Interaction and Learning (VAIL). Findings from a study of 270 preschool teachers suggest that the VAIL reliably measures teachers' interaction detection and identification skills. Teachers who can accurately detect effective interactions on video exemplars tend to have more years of education and display more effective interactions with the students in their classroom. Findings are discussed in terms of the implications for teacher selection, preparation, and training.