OBJECTIVES:  A substantial number of persons living with HIV (PLWH) have suboptimal ART adherence (<90%), which has implications for health outcomes. Despite empirical evidence that pharmacist interventions can increase ART adherence, pharmacists are underutilized resource in promoting ART adherence. Our objective was to examine how ambulatory-based pharmacists’ knowledge, motivation, and behavioral skills influence the provision of adherence promotion activities (APA) to PLWH METHODS:  188 ambulatory-based pharmacists providing HIV patient care rated 27 APA items and another 27 items related to the information-motivation-behavioral skills (IMB) model. We used Exploratory Factor Analysis (EFA) to identify latent constructs (APA, Information, Motivation, Behavioral Skills) and Structural Equation Modelling (SEM) with 2000 bootstrapping to assess the direct and indirect effects of IMB predictors on APA. We hypothesized that each IMB factor independently predicted APA, and that information and motivation indirectly predicted APA through Behavior Skills. RESULTS: EFA generated 1 APA factor (eigenvalue (λ)=5.11, variance explained (R)=58%, Cronbach alpha (α)=0.92) and 3 IMB-factors having λ>1 (1.25≤λ≥4.35; R=77%; 0.76≤α≥0.90). Initial SEM chi-square of p<.001 suggested the model failed to fit the data. Modification Indices suggested that Information was not a significant predictor of APA. After respecifying the model to exclude Information, all model fit indices fit the data well. All coefficients were statistically significant (p<.05), with correlations among factors ranging from -.29 to .33. The respecified model explained 58% of the variance in APA. CONCLUSIONS:  Our findings provide partial support for the IMB model, since Information does not predict APA. Information influences APA indirectly through motivation and behavioral skills. Motivation is a significant predictor of both behavioral skills and APA. Ambulatory-based pharmacists’ provision of APA is largely influenced by motivation-related factors. Thus, pharmacist-level interventions to promote ART adherence among PLWH in ambulatory-based settings should focus on increasing pharmacist motivation (e.g., reimburse for APA services).