This study assessed the moderating effects of school facilitating conditions (school opportunities for prosocial involvement, school commitment, academic grades, and truancy) on adolescent marijuana use within the context of the Theory of Planned Behavior (TPB). Utilizing a large statewide surveillance study of adolescent risk and protective factors (N = 217,276), Structural Equation Modeling was used to examine the extent to which TPB constructs (behavioral beliefs, normative beliefs, control beliefs, and behavioral intention) predicted adolescent marijuana use. Results revealed the TPB model provided adequate fit to the data (X[super script 2](127) = 58,042, p < 0.01, CFI = 0.95, TLI = 0.94, RMSEA = 0.04), with strong and significant pathways in the directions expected. TPB constructs explained approximately 60% of the variance in intention and 34% of reported marijuana use over the past 30-days; revealing an unexplained intention-behavior gap. To explore this gap, we examined the role of school facilitating conditions on the relationship between intention and marijuana use. After controlling for related TPB constructs, moderation tests of this pathway revealed higher levels of school opportunities for prosocial involvement and school commitment significantly reduced the relationship between intention and marijuana use. Poor academic grades and higher levels of truancy strengthened the relationship between intention and marijuana use. These findings indicate school facilitating conditions may play an important role in adolescent decision-making regarding marijuana use. Greater attention to these conditions may address the intention-behavior gap and enhance the effectiveness of school-based drug prevention programming.