OBJECTIVE: To examine patterns and predictors of trends in DSM-IV serious emotional disturbance (SED) among youths exposed to Hurricane Katrina. METHOD: A probability sample of adult pre-hurricane residents of the areas affected by Katrina completed baseline and follow-up telephone surveys 18 to 27 months post-hurricane and 12 to 18 months later. Baseline adult respondents residing with children and adolescents (4-17 years of age) provided informant reports about the emotional functioning of these youths (n = 576) with the Strengths and Difficulties Questionnaire (SDQ). The surveys also assessed hurricane-related stressors and ongoing stressors experienced by respondent families. RESULTS: SED prevalence decreased significantly across survey waves from 15.1% to 11.5%, although even the latter prevalence was considerably higher than the pre-hurricane prevalence of 4.2% estimated in the US National Health Interview Survey. Trends in hurricane-related SED were predicted by both stressors experienced in the hurricane and ongoing stressors, with SED prevalence decreasing significantly only among youths with moderate stress exposure (16.8% versus 6.5%). SED prevalence did not change significantly between waves among youths with either high stress exposure (30.0% versus 41.9%) or low stress exposure (3.5% versus 3.4%). Pre-hurricane functioning did not predict SED persistence among youths with high stress exposure, but did predict SED persistence among youth with low-moderate stress exposure. CONCLUSIONS: The prevalence of SED among youths exposed to Hurricane Katrina remains significantly elevated several years after the storm despite meaningful decrease since baseline. Youths with high stress exposure have the highest risk of long-term hurricane-related SED and consequently represent an important target for mental health intervention.