An overview of research studies on the relationship among time factors and student achievement is presented. The California Beginning Teacher Evaluation Study is cited as a seminal work in this area. A brief summary of findings on allocated time, engaged time, and academic learning time includes a discussion on how these studies have been expanded and refined by further studies. A discussion on how the "time for learning" concept has become a mechanism for studying other dimensions of the educational experience refers to studies on collective bargaining, bilingual education, mainstreaming, high and low achievement, minority and disadvantaged groups, nontraditional settings, and reading instruction. An analysis is presented of the problems and difficulties associated with observation as a research methodology in studying academic learning time. Implications for teaching are considered and some recommendations are made on ways in which the time-on-task concept can be used for the improvement of education. The concluding discussion offers suggestions on how time-on-task research can be integrated with other forms of research in teacher education programs. (JD)