I surveyed use of caves by bats in Puerto Rico. The exact location of each species of bat within the roost was determined for 17 caves. A comparison of variance was performed on the data to test the null hypothesis that occurrence of each species was independent of the others. Nonrandom associations were common among cave-dwelling bats in Puerto Rico. The species showing the strongest associations—Monophyllus redmani, Mormoops blainvillii, and Pteronotus quadridens and Erophylla sezekorni and P. parnellii—were associated with hot caves.