First-term attrition, defined as failing to complete the contracted first enlistment term, is one of the most serious and costly problems faced by the U.S. Navy. This study was an investigation of 1-year Navy attrition in relation to demographic factors and variables assessed by the Sailors' Health Inventory Program (SHIP) questionnaire, a medical and psychosocial history questionnaire completed by all Navy recruits. Overall attrition, as well as specific categories of attrition (e.g., medical, behavioral, and administrative), were studied. The sample consisted of 66,690 Navy recruits whose status (retention vs. attrition) could be tracked to the 1-year mark. The strongest predictors of overall attrition were educational level, self-reported history of shortness of breath, ever being suspended or expelled from school, history of depression/excessive worry, fainting or dizziness, and recurrent back pain. Many other medical and psychosocial items from SHIP were also predictive of attrition. Similar factors were associated with different categories of attrition (e.g., medical, behavioral). The implications of these findings for attrition reduction strategies are discussed.