Bringing to the field of third language (L3) research a new population of speakers, namely heritage speaker (HS) L3 learners, this study investigates the accents of 19 German-Italian HSs in L3 English. In an accent rating experiment, the speech samples of the HSs and three control groups (monolingual speakers of English, Italian, and German) were rated for 'degree of foreign accent' and 'source of accent'. The role of 'Italian use' and 'phonetic-phonological proficiency in Italian' was also investigated for patterns of cross-linguistic influence (CLI) into English. For 'degree of foreign accent', the HSs were rated as moderately accented, on par with German controls, but as weaker accented than Italian controls. For 'source of accent', the HSs were perceived as German-sounding in most ratings (66.8%), while an Italian-sounding accent was detected in certain HSs (9.5% of ratings). Regression analyses showed CLI from Italian to be significantly predicted by the amount of 'Italian use', measured using a detailed background questionnaire. We conclude that, while accent in L3 English is predominantly affected by German, the typologically closer and majority language, CLI from Italian co-occurs in speakers who used their heritage language frequently.