The early childhood professionals recognize the limitations of conventional testing with young children. This recognition has given rise to Authentic Assessment, now recognized officially as best practice by the major professional organizations. However, no national studies have been conducted to document the comparative qualities of either authentic or conventional approaches—according to meaningful external standards. Based on a national Internet survey of professionals, we report details of a social validity study of common measurement methods on eight operationally defined standards for developmentally appropriate assessment linked to professionally sanctioned practice standards and indicators. Approximately 1,500 professional responses reveal higher quality appraisals for authentic assessment over conventional testing methods for early childhood intervention purposes. Based on these results, we offer recommendations to advance valid, sensible, and contextually appropriate assessment for early childhood intervention.