Purpose: It is widely acknowledged that parental input plays an important role in typical language development. Less is known about the input provided to children with (suspected) developmental language disorder (DLD) or those at risk for DLD. These children may not benefit from parental input in the same way as their typically developing peers, and different aspects of parental input may be more important for them. The present systematic literature review aimed to uncover (a) how parental input has been assessed in the context of DLD, (b) which aspects of parental input have been studied, and (c) what the reported associations are with language outcomes in children with DLD (age 0--6 years). Method: A systematic literature review of 67 articles was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Parental input was coded based on Rowe and Snow's (2020) categorization of input, divided into interactive, linguistic, and conceptual aspects of parental input. Results: The majority of studies used audio or video recordings of naturalistic parent--child interaction during play. Aspects within the interactive dimension (parental responsiveness and turn-taking) were most often assessed, followed by the linguistic and conceptual dimensions. Thirty-eight studies investigated the relationship between parental input and child language outcomes. Findings show that aspects within the interactive dimension are positively associated with language outcomes in children with DLD. Additionally, the sheer quantity of language input was not associated with language outcomes, although replication of this observation is necessary. Conclusions: The results of this review highlight the importance of parents' responsive behaviors as well as the child's involvement in parent--child interaction. The findings also signal gaps in the existing literature and provide associated directions for future research on effects of parental input in children with DLD.