Early autumn has become a season of disaster anniversaries. In this issue an article by Wang and colleagues reminds us that whether or not the "cause" of a disaster is attributable to humans or to nature, the impact is a reflection of social forces.

The data reported by Wang and his coauthors may not surprise most services researchers. In the months after Hurricane Katrina and the region's evacuation, less than a third of those with symptoms of mental disorders received any services. Even among those with the most serious symptoms, most received no care. The authors note that these data mirror those reported in the wake of the September 11, 2001, terrorist attacks.

The statistical similarities in the post-9/11 and post-Katrina experiences mask striking differences. After the disaster in New York most research has focused on individuals who have posttraumatic stress disorder or other reactions to the attacks. There has been less focus on the service needs of individuals in New York who were already in the mental health system, in part because the attacks did not damage the city's service infrastructure. If anything, the infrastructure was strengthened by the response of the public and private sectors to increase services for the newly traumatized.

In contrast, pre-Katrina New Orleans faced the storm with a deficient health care system that produced some of the poorest health care indicators in the country. Nature may have brought Katrina to the city and the levees let the water in, but arguably it was the city's inability to cope that left the disaster unmitigated. New Orleans was already struggling to meet the mental health needs of its residents, especially those with serious mental illness. How could they—the mental health providers, their patients, or the general population—be prepared for the devastation, uncertainty, and displacement that came with the flood? Many providers were evacuated, leaving the city without its health care safety net for individuals with long-term or new mental illness. Displaced providers, like others, suffered the trauma of dislocation and the stress of being severed from normal life for months.

Visit New Orleans or Ground Zero and it is clear that even two years after Katrina and six years after the terrorist attacks, the concrete challenges to rebuilding remain enormous. The challenge of rebuilding New Orleans' services infrastructure is perhaps even greater. However, we also have an unprecedented opportunity for change and improvement of health care services. Too often, services are developed in response to crises and with little data to support our guesses. With effort and forethought, we can use the data reported by Wang and colleagues for the social good, helping us to resist the trap of recreating what we had before and to build a system that matches the needs of the population.