Purpose: Evidence has shown that group conversation treatment may improve communication and reduce social isolation for people with aphasia. However, little is known about the impact of conversation group treatment on measures of discourse. This project explored the impact of conversation treatment on measures of monologic discourse. Method: In this randomized controlled trial, 48 participants with chronic aphasia were randomly assigned to dyadic, large group, or control conditions. Conversation group treatment was provided for 1 hr, twice per week, for 10 weeks. Discourse samples were collected and coded at pretreatment, posttreatment, and 6-week maintenance. There were three narrative tasks: (1) Comprehensive Aphasia Test (CAT) picture description; (2) Cat Rescue Picture; and (3) Cinderella retell. All narratives were coded using the percent correct information units (percent CIUs), the CAT standardized narrative analysis method, and the complete utterance (CU) method. Results: No significant changes were observed on percent CIU, which was the primary outcome measure. The treated groups demonstrated improvement on aspects of the CU method following treatment, whereas the control group did not. Significant changes were observed for other CIU measures and the CAT standardized narrative analysis in both the treated and control groups. Conclusions: The results suggest that the CU measures were more sensitive to the effects of conversation treatment in monologic discourse compared to CIU and CAT measures. Changes were more common in absolute rather than relative values, suggesting that conversation treatment impacts the overall amount of language produced rather than efficiency of production.