This paper provides performance analyses of a broad spectrum of error-correcting codes in an antijam communication system under worst-case partial-band noise jamming conditions. These analyses demonstrate the coding advantages available for systems operating with and without frequency diversity. Utilizing both the exact approach (where possible) and upper-bounding approaches (Chernoff and union bounds), the decoded bit error rates for typical error-correcting codes (binary andM-ary, block and convolutional) have been obtained, and these codes have been compared according to theE_{b}/N_{0}required to achieve a bit error rate of 10-5. The best performance is achieved with the use ofM-ary signaling and optimum diversity withM-ary codes, such as Reed-Solomon block codes, dual-kconvolutional codes, convolutional orthogonal codes, or concatenated codes.