This document reviews government policies that have driven the use of anaerobic digestion (AD) in five nations: Australia, Denmark, Germany, the UK, and US. These nations were chosen as they represent a breadth of AD use, from 78 plants in Australia to 9545 plants in Germany. The review finds that energy security, climate change, and waste management policies have most significantly promoted AD adoption. Specifically, performance-based financial incentives for small-to-medium AD plants (<500 kW) in Germany and the UK strongly correlated with increased AD growth. While the AD industry faces barriers, supportive government policies addressing its wide-ranging benefits across areas like energy and waste can encourage greater investor interest.