Measuring in-hospital mobility of older adults with accelerometers is becoming more common practice. However, neither the unique challenges surrounding accelerometer use within acute hospital settings nor the potential solutions to these challenges have been well documented. The aim of this article is to present and discuss what occurs “behind the scenes” when using accelerometers to quantify in-hospital mobility among older adults in acute hospital wards. The article identifies the challenges related to accelerometer use that emerged over the course of daily data collection for 2 large-scale studies, including matters of recruitment, daily use, technical and methodological issues, loss of devices, missing data, and troubleshooting. The article details the tasks and the strategies we developed for overcoming these challenges and how we implemented them within the acute wards. Finally, the article provides recommendations for researchers and clinicians on how to improve future use of accelerometers or other devices aimed to enhance in- hospital mobility of older adults.