Faith-based organizations can be key settings in which to reach African Americans and Latinos for HIV prevention, but little is known regarding factors that predict congregants' HIV testing behaviors. We examined the extent to which sociodemographic factors, HIV-related cues to action (e.g., knowing someone who is HIV-positive), and the social climate surrounding HIV (stigma toward a hypothetical HIV-positive congregant, HIV-related discussions at church about abstinence, condoms, and testing) were associated with willingness to be tested in church and with ever having been tested among 1211 African American and Latino congregants. Multivariate analyses indicated that congregants were more open to church-based testing if they were younger and had discussed condoms at church. They were less open if they expressed stigmatizing attitudes toward a hypothetical congregant. Foreign-born Latinos with low English proficiency were more willing to be tested at church than were African Americans. Congregants were more likely to have ever been tested if they were younger, African American, female, or married; if they knew someone who was HIV-positive; and if they had discussed testing and condoms at church. They were less likely if they had discussed abstinence. Open dialogue around HIV may activate congregants to be more receptive to church-based prevention.