Statistical energy analysis (SEA) has been recently used to predict the sound transmission loss of single and double partitions [Price and Crocker, J. Acoust. Soc. Am.47, 683 (1970)]. The present authors have applied a similar SEA technique to the problem of sound transmission between two adjacent rooms whose walls, floor, and ceiling are all structurally coupled. The model examined consisted of a rectangular box separated into two cavities by a dividing partition. The SEA model therefore consisted of five coupled resonant elements: the source room, the source and receiving room common sidewalls (assumed to be identical in each of the two rooms), the dividing partition, and the receiving room. The theory considers the effects of the material thickness and damping of both the dividing partition and the coupled sidewalls. Wave interaction at the structural junctions of the partition and the sidewalls was also examined and used to predict the required structural coupling loss coefficients. The theory was found to produce good agreement from 500 to 16 000 Hz (±2 dB) with experimental data obtained from a pair of model rooms. It is shown that by careful selection of system parameters, the effects of structure‐borne flanking can be minimized.