This study examined various client related factors that may predict problem gambling (PG) treatment outcomes (i.e., treatment completion and continued abstinence). Specifically, factors that may facilitate treatment (i.e., social support, self-efficacy, motivation, readiness for change, and emotion-focused coping) or hinder treatment (i.e., depression and life stress) were examined. The 50 participants were followed for four months after entering treatment for PG and were assessed at baseline, one month into treatment, two months into treatment, and during a follow-up four months after treatment began. Of the 50 participants, 20 dropped-out of treatment and 24 completed the follow-up measure. The results suggest that self-efficacy and depression, measured at baseline, are good predictors of one and two month outcomes, whereas depression and life stress, measured after two months of treatment, are good at predicting four month outcomes. The results also suggest that younger individuals have different predictors for dropout than do older individuals. The treatment implications of the findings are discussed.