This study assessed whether attitudes towards STI screening, visiting a clinic and having an STI (STI stigma) predict STI screening attendance in young adults. Participants (N = 217) rated each of these attitudes and completed measures assessing their STI knowledge, past sexual behaviour and sexual health. STI stigma and having favourable attitudes towards STI screening positively predicted screening attendance. People were less likely to attend if they had a negative attitude towards visiting sexual health clinics. Researchers should assess attitudes towards the attitude object (screening), condition (STI stigma) and process (visiting a clinic) to understand the different ways that attitudes predict behaviour.