Background: Parental communication deviance (CD) has long been suggested as a potential risk factor for the development of psychosis and thought disorder in genetically sensitive offspring. However, the findings of the studies on the prevalence of CD in parents of psychotic patients have never been submitted to quantitative synthesis. Method: PsycINFO was searched from January 1959 to January 2012 for studies on the prevalence of CD in parents of psychotic patients. This search was supplemented with the results from a much larger systematic search (PsycINFO, PubMed, EMBASE, and Web of Science) on childhood trauma and psychosis. Results: A total of 20 retrieved studies (n = 1753 parents) yielded a pooled g of large magnitude (0.97; 95% CI [0.76; 1.18]) with a significant amount of heterogeneity (Q = 33.63; P = .014; I2 = 46.47). Subgroup and sensitivity analysis of methodological features (study’s design, comparison group, diagnostic criteria, CD rating method, inter-rater reliability not reported, year of publication, and verbosity) and demographic characteristics (level of education or offspring’s age) revealed that pooled effect size was stable and unlikely to have been affected by these features. Conclusion: CD is highly prevalent in parents of psychotic offspring. This is discussed in the broader context of adoption and longitudinal studies that have reported a G × E interaction in the development of psychosis and thought disorder. A potential developmental mechanism is suggested to explain how CD may affect the developing offspring. The importance of further studies on CD and its potential value as a clinical concept are discussed.