Systematic reviews of literature relevant to early intervention and early childhood services are important to the practice of occupational therapy. We describe the five questions that served as the focus for the systematic reviews of the effectiveness of occupational therapy interventions in early intervention and early childhood services. We include the background for the reviews; the process followed for each question, including search terms and search strategy; the databases searched; and the methods used to summarize and critically appraise the literature. The final number of articles included in each systematic review; a summary of the themes of the results; the strengths and limitations of the findings; and implications for practice, education, and research are presented.