Abstract: A modular photographic flash system includes a plurality of housings, some possibly empty and some containing flash units, interconnected to form a desired flash unit array. Each housing includes a hollow cylindrical member substantially square in transverse cross-sectional outline with two adjacent walls having dovetail tongues thereon and the other two walls having dovetail grooves to accommodate interfitting of adjacent housings. A latch member is movable into and out of each dovetail groove for engagement in an associated slot in the tongue interfitted therewith, the latch being operated by a spring-biased actuator rod carried in a channel formed in the inner surface of the housing.