A discussion of the N.L.R.B.’s policy with respect to cases allegedly involving both an arbitrable grievance under a collective bargaining agreement and an unfair labor practice under the National Labor Relations Act. The author examines the potential conflict between arbitration and Board decisions in three general areas: the individual discharge; the refusal to supply information for purposes of collective bargaining; and disputes between competing groups of employees as to the assignment of work. The author details some ways that the prior arbitration award can help the Board determine appropriate action.