In line with emerging trends examining sentence processing in heritage language (HL) bilingualism and adopting an individual differences approach, the present study investigated the role of prediction and lexical interference in 68 Russian HL bilinguals in North America. The former was investigated by examining how Russian HL bilinguals processed sentences with semantically constraining verbs, whereas the latter was assessed examining how contextually globally irrelevant but locally coherent color word information is processed. The findings revealed that, as a group, participants demonstrated predictive processing and were subject to lexical interference. To understand inter-participant variation, we examined the roles prediction and/or interference play as a function of individual differences in cognitive control (as measured by a Flanker task), performance on vocabulary and gender knowledge tasks as well as participants’ individual language history and use (LHQ3, Li et al., Biling Lang Cogn 23:938–944, 2020). Indeed, these analyses revealed that individual language knowledge and domain-general cognitive control play crucial roles in how prediction and/or interference play out in HL processing.