This study assessed the immediate and short-term outcomes of adapting a culturally-grounded middle school program, "keepin' it REAL", for elementary school students. After curriculum adaptation, 10 schools were randomly assigned to the intervention in 5th grade with follow-up boosters in 6th grade; 13 schools were randomly assigned to the control condition, implementing the school's pre-existing substance use prevention programming. Students (n = 1,566) completed a questionnaire prior to curriculum implementation and follow-up questionnaires toward the end of 5th and 6th grade. The 5th grade "kiR" curriculum generally appeared no more effective than the control schools' programming in changing students' resistance or decision-making skills; substance use intentions, expectancies, or normative beliefs; or lifetime and recent substance use. Such findings have implications for the age appropriateness of school-based programs. (Contains 4 tables and 2 footnotes.)