American building trades unions have historically played a critical and stabilizing role in the nation’s construction industry, establishing uniform standards and leveling the competitive playing field. Union members have enjoyed better than average wages and benefits, excellent training opportunities, and decent jobsite conditions. But in the last thirty years the industry has undergone a dramatic transformation. This article describes the decline in union density, the drop in construction wages, the growth of anti-union forces, the changes in labor force demographics, the shift toward construction management, and the emergence of an underground economy. It also analyzes how building trades unions have responded to these changes, identifies structural impediments to union renewal, and proposes strategies for building trades unions to reassert their presence and power.