Today, vulnerable populations expand as the threats of homelessness and communicable diseases continue to grow. Volunteers are moved to serve in areas in which they may not be well prepared. We identify the caring needs of high-risk, vulnerable populations and the needs of volunteers; we also conceptualize, develop, implement, and evaluate a training program for volunteers who serve homeless persons and families. This training program and the imperatives that undergird it are presented as a model applicable to the training of volunteers serving high-risk, vulnerable populations.