The U.S. Department of Defense (DOD) workforce is made up of approximately 3.7 million people. To shape a “larger, more capable and more lethal joint force,” we consider opportunities for DOD to optimize its workforce across the dimensions of military, civilian, and contractor personnel; active duty, reserve, and National Guard personnel; officer, warrant officer, and enlisted personnel; and human performers versus technology substitution. Focusing on the expeditionary, training, and medical workforces, we summarize what is currently known about which labor types are best suited for a given objective, illuminate knowledge gaps, highlight currently actionable research insights, and outline strategic research questions to pursue now in advance of tomorrow’s information demands.