Purpose: Treatment response is the degree to which an individual benefits from a treatment. This systematic review sought to identify and synthesize research evidence regarding individual characteristics that predict language treatment response among children with developmental language disorder (DLD). Method: To be eligible for inclusion, articles needed to report results of an oral language treatment program in a group of children aged 4-10 years with identified DLD and also include a quantitative analysis of the relation between one or more pretreatment child characteristics and the outcome of language treatment. Seven databases (Cumulated Index to Nursing and Allied Health Literature, Dissertations and Theses Global, Education Resources Information Center, Linguistics and Language Behavior Abstracts, PsycINFO, Medline, and Web of Science) were searched for articles in June and July 2021, with search updates conducted in May 2023. Studies were categorized by the type of treatment provided, and results were synthesized qualitatively. Results: The review included 31 studies, 1,551 participants with DLD, and over 300 statistical tests of a predictor's effect on language treatment response. Most studies (n = 21) included only monolingual speakers of English, with five studies including bilinguals and five including monolingual speakers of non-English languages. Language treatments targeted word learning in controlled or clinical conditions, grammatical learning in controlled or clinical conditions, or multiple language targets in clinical conditions. Predictors of treatment response are summarized across four categories: cognitive, demographic, pretreatment language levels, and other. Conclusions: There were relatively few significant tests of the predictors of language treatment response. A central limitation of the evidence is that most included studies were designed to consider language treatment efficacy, not predictors of treatment response. Increasing research attention to the question of predictors of language treatment response in children with DLD is needed to enhance treatment and optimize outcomes for individual children.