This article describes a psychotropic PRN Evaluative Tool developed by interprofessional clinicians to address inconsistent reporting and assessment of the effectiveness of PRN medications used for people who are developmentally disabled. Fifty-nine participants (37 males, 22 females), ages 16 to 60 years, were included in the review, all diagnosed with an intellectual disability and a serious mental illness. Participants' range of intellectual disability varied from severe to mild. The review was conducted over a 2-year period. Data was evaluated by comparing differences in a number of patient pre and post behaviors after having received PRN medication. Results indicated a statistically significant decrease in the total number of post-PRN behavior variables observed compared with the pre-PRN behavior variables. This tool has improved patient outcomes through the reduction of unnecessary and/or ineffective PRNs by providing a more thorough assessment of the effectiveness of PRN medications and thereby reducing subjective and ambiguous language.