Narrative story stem measures are increasingly popular for the assessment of attachment representations among early school-age children. Given their clinical and theoretical importance, disorganized representations are typically a focus of assessment procedures. The Manchester Child Attachment Story Task (MCAST) is one such measure. A systematic literature review and meta-analysis was conducted to evaluate the documented reliability and validity of the MCAST with a focus on assessing disorganized representations. Twenty-five studies were included in the review encompassing 1,876 children from nine countries. Results suggest that inter-rater reliability for the MCAST is acceptable and the prevalence of disorganization identified on the MCAST among various subgroups (e.g. community, clinical, adopted/maltreated) is comparable to prevalence estimates from other developmental periods using other assessment methods. In addition, prevalence of disorganization on the MCAST differed in hypothesized ways between the various subgroups. However, MCAST disorganization did not correlate in predictable ways with many constructs when relationships were examined within samples. Few studies examined the relationship of disorganization on the MCAST with parenting variables, aspects of adoption and maltreatment, and emotion regulation skills. Recommendations for further study of the MCAST and for how the tool might be integrated into clinical and developmental research are provided.