The majority of prisons today have an internal grievance mechanism that gives inmates an opportunity to air complaints and seek solutions to individual and institution-wide problems. This study reports on the way the mechanism functions at two Illinois state prisons—one minimum security and one maximum security. The main findings are: (1) that the mechanism is heavily and repetitively used by only a portion of the inmate population, (2) that the grievances filed range widely in type as well as in merit, although it is clear that there is much frivolous activity, (3) that inmates win only a small percentage of their cases, either at the first-instance level or on appeal, and (4) that among both line prison staff (at least at one of the prisons) and inmates there is considerable dissatisfaction with the process, although a minority of prisoners and the higher echelon prison administrators can be counted on for more favorable assessments. The article goes on to compare these findings with the generally articulated objectives of the grievance process and concludes with a series of suggestions that have been made for improving its workings.