The attenuation of the first acoustic normal mode was measured for sound propagation in shallow water off the coast of Daytona Beach, Florida. The use of small explosive charges as a source permitted mode attenuation measurements over a frequency range extending from 40 to 800 Hz. Isolation of the first mode was accomplished by selecting source and receiver depths to minimize excitation and reception of the second and third acoustic normal modes. Higher order modes decayed rapidly with range and hence constituted a negligible contribution to the received pressure field. The results obtained from short range measurements are compared with long range propagation loss. [Work supported by the Naval Sea Systems Command.]