A random ratio schedule is one under which every ordinally specified response has the same probability of reinforcement as any other. Data have been gathered at several values of this type of schedule, using a separate group of pigeons for each schedule value and giving prolonged exposure to each value. No simple relationship was found between response rate and reinforcement probability. In general aspect group data from the present experiment agree with those from a single organism study cited. It was shown that 40 to 50 days of exposure to random ratio schedules yields fairly asymptotic response rate data. The tabulated raw data, and the results of some statistical manipulations, have been deposited with the American Documentation Institute.