In general, animals prefer to mate with individuals they have observed being courted or in close association with sexual partners. This phenomenon of mate copying has been demonstrated in several species, but so far no study has provided substantial evidence that it is adaptive. Furthermore, mate copying has been viewed only in the context of females copying other females or males copying other males. In the peacock blenny, Salaria pavo, parasitic males (sneakers) may gain an advantage by copying the association patterns of females with bourgeois males (large males that defend nests). We tested the sneaker's preference for one of two males and subsequently presented the nonpreferred male to the sneaker in the company of females, while the preferred male was presented alone. If the association of females with bourgeois males influences the sneaker's preference, we predicted the sneaker would spend more time close to the nonpreferred male, when females were no longer present. We found that (1) sneakers preferred to associate with the larger of the two males and (2) when the previously nonpreferred male was presented in the company of females the sneakers tended to approach that male sooner, although not significantly so, and to spend more time close to it. Thus, parasitic males seem to choose host males both by independent mechanisms (larger males were preferred) and by nonindependent mechanisms (males observed with females were preferred). We discuss the adaptive value of sneakers choosing males by each of these mechanisms.