Almost all professional sporting disciplines organized as leagues have organizations representing their athletes. These groups have far higher membership rates than major affiliated labor unions. Yet there have so far been few studies on this or on how these organizations operate. Based on interviews with union representatives and documentary research, this study shows that unionism in sport expresses itself in its own particular way. This is far from the typical image of protest or militant unionism serving political and social ideology. Actions carried out by organizations representing sports professionals are fashioned as “useful services for sports professionals.” By primarily focusing on the sporting discipline, these labor unions are anchored in the idea of sectoral service.