Microhabitat specialists offer tractable systems for studying the role of habitat in determining species’ distribution and abundance patterns. While factors under- lying the distribution patterns of these specialists have been studied for decades, few papers have considered factors influencing both the microhabitat and the inhabitant. On the Belizean barrier reef, the obligate sponge-dwelling goby Elacatinus lori inhabits the yellow tube sponge Aplysina fistularis. We used field data and multivariate analyses to simultaneously consider factors influencing sponge and goby distributions. Sponges were non-ran- domly distributed across the reef with density peaking at a depth of 10–20 m. Sponge morphology also varied with depth: sponges tended to be larger and have fewer tubes with increasing depth. Knowing these patterns of sponge distribution and morphology, we considered how they influenced the distribution of two categories of gobies: residents (C18 mm SL) and settlers (18 mm SL). Maxi- mum tube length, number of sponge tubes, and depth were significant predictors of resident distribution.