Intervention studies to reduce challenging behavior in young children below the age of 6 were reviewed for participant characteristics, including gender, race/ethnicity, disability, socioeconomic status, and language to evaluate the frequency of reporting and diversity of participant characteristics in this area of research. Interventions conducted in school, preschool, and home-based settings were included; 53 articles were reviewed. In these articles utilizing single case research or group designs (n = 2,262 participants), most articles reported gender and disability. Slightly fewer than half of the studies reported participants' race/ethnicity. Socioeconomic status and language were infrequently reported. Analyses of participant characteristics in studies that reported children's gender and race/ethnicity found that boys and Black and Latino children were overrepresented. Implications are discussed, including the field's use of research standards regarding the reporting of participant characteristics, suggestions for inclusive recruitment and retention strategies, and the importance of identifying culturally responsive interventions for challenging behavior.