There are many instances when the detection of an object lying on the seafloor is insufficient. In many cases, an idea of what kind of object is lying on the seafloor is also required. The detection and classification sonar described here is based on a wide bandwidth continuous transmission frequency-modulated (CTFM) sonar. The design and operating parameters of CTFM sonars are discussed in some detail with particular reference to their use as classification sonars. One type of CTFM sonar incorporating a technique to eliminate the ‘‘blind time’’ and extend the maximum range is chosen to implement several detection and classification schemes. It is shown that of the various classification schemes used, the one based on a simple rough/smooth discrimination was the most reliable. This reliability was judged by comparison to an alert human operator with access to a variety of visible and audible displays. It was found that the algorithm performed nearly as well as the operator and is of course faster and not subject to fatigue. Many results are illustrated.