Urban growth boundaries (UGBs) or “urban edges” as they are known in South Africa have been widely implemented by cities internationally with the intention of curbing urban sprawl. However, technical complexities and high levels of contestation frequently present challenges for their implementation. In particular, it is important to ensure that their demarcation includes appropriate land reserves to accommodate urban growth. Drawing the boundary too tightly can stifle economic growth and lead to land price increases, while including too much land within the UGB may result in unchecked urban sprawl and its associated environmental, social and financial costs. The aims of this paper are firstly to review international and local literature with reference to the merits and appropriateness of UGB policies and secondly to consider methods used by cities internationally to determine UGBs and describe the method used by the City of Cape Town to review its UGB in 2010. The Cape Town method evaluates land reserves against urban growth forecasts and is consistent with methods generally used by US cities. However, a number of adaptations for local and rapidly urbanising third world environments are outlined. The Cape Town method is evaluated with reference to the literature and lessons learnt are discussed. Key findings include the value of rigorous, defensible methods and clear policy guidelines in a contested environment, the value of integrating UGB reviews within broader land-use planning processes, the usefulness of information generated for broader urban planning processes and the utility of accurate information on past trends in moderating growth expectations.