This study examined medication decision making by 84 persons with serious mental illness, specifically examining relationships among perceived coercion, decisional capacity, preferences for involvement and actual participation, and the outcomes of medication adherence and QoL. Multiple and logistic regression analysis were used in this cross-sectional, descriptive study, controlling for demographic, socio-economic and utilization variables. Appreciation was positively related to medication adherence behaviors for the past six months. Females, older individuals and those living independently were more likely to have taken all their medications over the past six months. Neither client participation, preference, nor preference-participation agreement was found to be associated with better medication adherence or QoL.