There has been inadequate consideration of how flow and meaning impact health within music therapy interventions. The purpose of these analyses was to determine if flow and meaningfulness of songwriting were related to and functioned as predictors of therapeutic outcome within songwriting interventions for adult inpatients on an acute care psychiatric unit (Study 1) and a detoxification unit (Study 2). Correlational and multiple regression analyses were conducted on data with inpatients who had participated in a single-session highly structured blues songwriting intervention with a music therapist. Therapeutic outcomes were state indices of hope (Study 1; N = 54 adults on an acute care psychiatric unit) and readiness to change (Study 2; N = 170 adults on a detoxification unit). In both studies, there tended to be positive and significant correlations between flow and meaningfulness of songwriting and therapeutic outcomes. Multiple regression analyses indicated that flow was a significant predictor of therapeutic outcome but that meaningfulness of songwriting was not a significant predictor of therapeutic outcome during both studies. Flow may represent a positively framed and less invasive method for measuring patients’ perceptions of the therapeutic outcomes. Implications, limitations, and suggestions for future research are included.