This article describes the development and validation of the Developmental Snapshot, a 52-item parent questionnaire on child language and vocal communication development that can be administered monthly and scored automatically. The Snapshot was created to provide an easily administered monthly progress monitoring tool that enables parents to better recognize language milestones and offers professionals prompt information to fine-tune intervention strategies. Initial items were piloted by 15 families; refinement and further development of the instrument was conducted with parents of 308 typically developing children. Reliability and criterion validity metrics were examined on subsets of approximately 60 children who completed the Snapshot on a monthly basis and who were evaluated on standard assessments administered by speech language pathologists (SLPs). Divergent validity was also examined for samples of children diagnosed with language delays related to autism spectrum disorder (ASD) (n = 77) or not (n = 49). Results supported the criterion validity (r = 0.67-0.97) and test-retest reliability claims of the Snapshot (r = 0.95). Sensitivity and specificity for language delay detection also were good at 87%. Potential applications for progress monitoring, fidelity of intervention, and enhancing parents' awareness of their child's language and vocal communication changes are discussed.