Randomized control trials are considered the pinnacle for causal inference. In many cases, however, randomization of participants in social work research studies is not feasible or ethical. This paper introduces the co-twin control design study as an alternative quasi-experimental design to provide evidence of causal mechanisms when randomization…

This paper reviews research on the design and effectiveness of preschools in the United States. Three randomized controlled trials that enrolled roughly 350 total children in demonstration studies during the 1960s and 1970s shape much of the current discussion of preschool. We examine what these studies and more recent ones based on random…