In 2005, Hurricane Katrina resulted in long-term flooding of 80% of New Orleans, Louisiana. Mold-infested homes gave rise to concerns about increased childhood asthma. To address these concerns, a diverse community-academic partnership used a community-based participatory research (CBPR) approach to implement the Head-off Environmental Asthma in Louisiana (HEAL) study in 2007.The study examined the relationship between post-Katrina mold and other environmental exposures and asthma morbidity, while testing an asthma counselor (AC) intervention. Both the AC intervention and the CBPR approach were effectively implemented in the postdisaster setting. However, homes had lower levels of mold and other allergens than expected, possibly because of the timing of environmental sampling. Also, HEAL illustrated the vulnerability of the study community, especially to the interconnected threats of health disparities, environmental health stressors, and disasters.We examine the implications of these threats for public health science, policy, and practice, not only through the lens of Hurricane Katrina but also for future disasters faced by communities in the Gulf Coast and nationally.