Health research on personal social capital has often utilized measures of respondents' perceived trust of others as either a proxy for one's social capital in the absence of more focused measures or as a subjective component of social capital. Little empirical work has evaluated the validity of such practices. We test the construct validity of two trust measures used commonly in health research on social capital-generalized trust and trust of neighbors-with respect to measures of people's general network-, organization-, family-, friend-, and neighborhood-based social capital and the extent to which these two trust measures are associated with self-rated general health and mental health when social capital measures are included in the same models. Analyses of 2008 Canadian General Social Survey data (response rate 57.3%) indicate that generalized trust and trust of neighbors are both positively-yet modestly-associated with measures of several domains of network-based social capital. Both trust measures are positively associated with general and mental health, but these associations remain robust after adjusting for social capital measures. Our findings suggest that (a) trust is conceptually distinct from social capital, (b) trust measures are inadequate proxies for actual personal social networks, and (c) trust measures may only be capturing psychological aspects relevant to-but not indicative of-social capital. Though links between perceived trust and health deserve study, health research on social capital needs to utilize measures of respondents' actual social networks and their inherent resources.