Surprisingly little is known about transgender attitudes, due in part to a need for improved measures of beliefs about transgender people. Three studies introduce and validate a novel Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) assessing implicit attitudes towards transgender people. Study 1 (N = 294) found significant implicit and explicit preferences for cisgender over transgender people, both of which correlated with transphobia and transgender-related policy support. Study 2 (N = 1094) found that implicit transgender attitudes predicted similar outcomes among participants reporting no explicit preference for cisgender versus transgender people. Across Study 3a (N = 5647) and Study 3b (N = 2276), implicit transgender attitudes predicted multiple outcomes, including gender essentialism, contact with transgender people, and support for transgender-related policies, over and above explicit attitudes. This work introduces a reliable means of measuring implicit transgender attitudes and illustrates how these attitudes independently predict meaningful beliefs and experiences.