This pilot study tested the efficacy of a brief intervention using motivational interviewing (MI) plus mindfulness meditation (MM) to reduce marijuana use among young adult females. Thirty-four female marijuana users between the ages of 18 and 29 were randomized to either the intervention group (n = 22), consisting of two sessions of MI-MM, or an assessment-only control group (n = 12). The participants' marijuana use was assessed at baseline and at 1, 2, and 3 months posttreatment. Fixed-effects regression modeling was used to analyze treatment effects. Participants randomized to the intervention group were found to use marijuana on 6.15 (z = -2.42, p = .015), 7.81 (z = -2.78, p = .005), and 6.83 (z = -2.23, p = .026) fewer days at Months 1, 2, and 3, respectively, than controls. Findings from this pilot study provide preliminary evidence for the feasibility and effectiveness of a brief MI-MM for young adult female marijuana users.