Military operations in Iraq and Afghanistan have brought increased attention to posttraumatic stress disorder (PTSD) among service members and, more recently, its impact on spouses. Existing research has demonstrated that PTSD among service members is associated with depression among military spouses. In the current study, we extended these findings by using data from service member–spouse dyads enrolled in the Millennium Cohort Family Study for which the service member had evidence of PTSD (n = 563). Prospective analyses identified the association between PTSD symptom clusters reported by the service member and new‐onset depression among military spouses. Over the 3‐year study period, 14.4% of these military spouses met the criteria for new‐onset depression. In adjusted models, service member ratings of symptoms in the effortful avoidance cluster, odds ratio (OR) = 1.61, 95% CI [1.03, 2.50], predicted an increased risk of new‐onset depression among military spouses, whereas reexperiencing symptoms, adjusted OR = 0.57; 95% CI [0.32, 1.01], were marginally protective. These findings suggest that PTSD symptom clusters in service members differentially predict new‐onset depression in military spouses, which has implications for treatment provision.