Research in early intervention/early childhood special education (EI/ECSE) is focused on identifying effective practices related to positive outcomes for young children with disabilities and their families. Individual responses to evidence-based practices are often variable, and non-responders are common. Single case research (SCR) might be particularly well suited to examining differences across participants given the dynamic nature of the methodology. The repeated measurement of behaviors and visual analysis of subsequent data allow researchers to continually monitor behavior and make necessary adaptations to ensure positive child outcomes. The purpose of this article is to illustrate the dynamic nature of single case research design (SCRD) and the utility of SCRD in the iterative development of adaptive evidence-based practices using three examples of SCR studies. Implications for research and practice in EI/ECSE are discussed.