A systematic literature review was conducted to evaluate previous research that examined intellectual disability (ID) or autism spectrum disorder (ASD) in relation to memory distortions (i.e. suggestibility and false memories). There were two goals for the current study; the first goal was to identify significant trends in past literature that fulfilled previously established selection criteria. The second goal was to establish reliability and effect sizes for suggestibility and false memory for samples with diagnoses of ID or ASD. Articles that were selected for inclusion in the current study were required to have a clinically diagnosed sample, as well as a non-clinical control group. Studies were also required to have a post-hoc power score higher than .30 to prevent the effects of underpowered studies and limit the potential for publication bias. Selected studies were also required to have provided pertinent information required to complete the analyses (e.g. means, standard deviations, p-values, or correlation coefficients). Any study that did not provide the required information was excluded. Two empirical Bayes omnibus analyses revealed a significant effect for participants diagnosed with ID (z = 6.10, p < .001), which supported the researchers' hypothesis. The results indicated increased susceptibility toward memory suggestibility and false memories when compared with the general population. However, the results of the analyses did not support the researchers' hypothesis regarding participants diagnosed with ASD. The analyses indicated that participants diagnosed with ASD displayed decreased suggestibility and were less likely to develop false memories (z = -2.37, p = 0.018). © 2019 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.