Multiple behavior change interventions have gained traction in the behavioral health space. Yet, previous studies on health coaching (HC) focused on testing its effect on stages of change for individual health behaviors. The purpose of this study was to examine the effects of HC on stages of change across multiple health behavior domains among patients at high risk of coronary heart disease and type 2 diabetes. This secondary analysis of a randomized clinical trial included 200 primary care patients (mean age of 47.7 years, 49.0% women, 60.5% Whites) who completed transtheoretical model-based questionnaires related to weight reduction, exercise, healthier eating, and stress management. Multigroup latent transition analysis was used to compare the stage of change distributions and transitions over time between HC and controls at baseline, midpoint of the intervention (3 months), and postintervention (6 months). Three distinct categories of behavior change were identified ("Contemplation," "Preparation to Action," and "Action"), and membership in these categories changed over time as a function of intervention exposure. Both groups exhibited positive transitions through stages of change from baseline to 3 months. Pronounced intervention effects emerged from 3 to 6 months, revealing larger differences in transition probabilities between the groups. In particular, HC increased patients' likelihood of transitioning from "Contemplation" to both "Preparation for Action" and "Action," as well as from "Preparation for Action" to "Action." The control group remained stagnant during the same period. Although HC produces changes across multiple behavioral domains, it was most effective for patients who were reluctant or ambivalent about changing their behaviors.