Objectives: Our goals are to: (a) determine pre- and immediate post-deployment factors predicting later MUI and poor functional status, (b) improve previous methodological problems (e.g., selection bias, recall bias and lack of baseline controls) in studies of MUI, and (c) relate pre-deployment risk factors (e.g., personality, stressor reactivity) and resilience factors (e.g., coping style, social support) to post-deployment functional status.