Healthcare professionals are the “first line of defense” in diagnosing and treating human and animal illness caused by OHH threats, and accurate diagnosis and reporting of these illnesses is critical to public health and the integrity of surveillance data. Garnering participation from healthcare communities was identified as an OHH priority during annual meetings of OHH Centers, and the focus of breakout sessions involving physicians and epidemiologists familiar with OHH and environmental health. The WHCOHH CEC is developing and implementing specific strategies to engage collaborators from the medical and environmental health communities to create and deliver materials to these health care professionals. As this is a comparatively new area of collaboration in OHH, some of these efforts are exploratory in nature and intended to lay the groundwork for future engagement efforts.