Direct support professionals (DSPs) provide people with intellectual and developmental disabilities (IDD) with individualized, personal assistance in a wide variety of settings. There is currently a very high turnover for DSPs, due in part to a lack of training for DSPs. The aim of this study is to explore how ongoing staff development impacts the health and safety of people with IDD. Our research question was: how does ongoing staff development, geographic location, and agency size impact the health and safety of people with IDD? To explore this research question, we analyzed data from 74 human service organizations which supported 8264 people with IDD, particularly examining the relationship between ongoing staff development from the Basic Assurances® and health and safety data regarding abuse and neglect, emergency room visits, and injuries. Our findings revealed that by simply offering ongoing staff development, human service agencies can potentially radically improve their service provision, and by extension the health, safety, and human security of the people with IDD they support. Ongoing staff development is an investment not only in the quality of services and supports DSPs provide to people with IDD, but also DSPs themselves.