Despite encouraging findings that show that interventions can improve students' math understanding, achievement gaps in math often persist or even widen for students who struggle. Practitioners play a significant role in closing these achievement gaps because they have the responsibility to select or design interventions. Practitioners may wish to consider factors that influence intervention effectiveness. This study evaluated numeracy interventions and explored how features of the studies and interventions may have influenced reported effects. Exploratory analyses revealed smaller effects when only distal measures were considered (g = 0.35; SE = 0.05), or when studies reported including more than 30 percent of participants as English learners (g = 0.44; SE = 0.12). Results also indicated variable effects across the same intervention programs. Implications for practitioners related to selecting interventions are discussed.