In recent years, historian and social activist Staughton Lynd has an advanced his theory of solidarity unionism as a way to rebuild the labor movement from below. To date, there have been relatively few unions organized using Lynd's theory and even fewer articles reflecting upon its utility for organizing. This essay critiques solidarity unionism by drawing upon the author's experience using Lynd's theory to build the Chicago Couriers Union (CCU). The history of the CCU is documented with primary sources including union newsletters, meeting minutes, and interviews with union organizers. Its successes suggest solidarity unionism's strengths while its failures point to ways in which the theory might be adjusted to gain greater utility.