—The performance of a cooperative network with Cooperative Maximal Ratio Combining (C-MRC) is analyzed. To this end, we propose a heuristic approximation to the total received SNR (signal-to-noise ratio) at the destination. The approximation is not only an accurate representation of the received SNR, but also amenable to performance analysis. We then derive the probability density function (PDF) of the approximate SNR. The PDF is used to derive expressions of the parameters required for the performance analysis of rate adaptive transmission, based on the use of a discrete set of modes of square M-ary quadrature amplitude modulation (QAM), with a cooperative network employing C-MRC. Analytical expressions for mode selection probability, the outage probability, the average spectral efficiency, and the average bit error rate are derived. Results show that performance of the system under C-MRC is comparable with other cooperative networks.