Unsubmitted sexual assault kits (SAKs) that accrue in U.S. law enforcement agencies (LEAs) have been the subject of increasing attention for the past decade, as have untested SAKs pending analysis in crime laboratories. The field needs a research-informed approach to identify the most efficient practices for addressing the submission of SAKs in LEAs and the testing of SAKs in laboratories. This approach would also determine whether specific policies or characteristics of a jurisdiction result in more efficient processing outcomes. This mixed-methods study examined intra- and interagency dynamics associated with SAK processing efficiency in a linked sample of crime laboratories (N = 145) and LEAs (N = 321). Relying on responses to a national survey of laboratories and a matched sample of LEAs, researchers at RTI International used regression analysis and stochastic frontier modeling to assess how labor and capital inputs, evidence policies, evidence management systems, and models of cross-agency coordination affect SAK processing efficiency. Semistructured interviews with personnel from forensic laboratories, LEAs, and prosecutor's offices in six jurisdictions were used to elaborate on critical themes relating to SAK processing efficiency.