Libraries are now several years into integrating tablets and smartphones into programs and services. It's possible to take stock of what's working and what isn't, and this issue of Library Technology Reports gathers five case studies involving the use of mobile devices in library service, viewing the potential benefits alongside real-world constraints. Advocating for assessment at the local level, the editors selected case studies notable for intentional integration of technology, lending perspectives useful for any library managing new technology. Touching on circulation, teaching, and access, the case studies examine such topics as: a library-based lab for testing web interfaces and user experience with a variety of mobile devices; expanding the reach of library instruction with mobile devices; circulating iPads; responsive web development at OCLC; anddeveloping an assessment plan and framework.