This article describes major topics covered during the ‘Economics of Physical Inactivity Consensus Workshop’ (EPIC), held in Vancouver, Canada, in April 2011. In particular, it (1) details existing evidence on effective physical inactivity prevention strategies; (2) introduces economic evaluation and its role in health policy decisions; (3) discusses key challenges in establishing and building health economic evaluation evidence (including accurate and reliable costs and clinical outcome measurement) and (4) provides insight into interpretation of economic evaluations in this critically important field. It was found that the majority of methodological challenges are related to (1) accurately and objectively valuing outcomes; (2) determining meaningful clinically important differences in objective measures of physical inactivity; (3) estimating investment and disinvestment costs and (4) addressing barriers to implementation. It is proposed that guidelines specific for economic evaluations of physical inactivity intervention studies be developed to ensure that related costs and effects are robustly, consistently and accurately measured. This will also facilitate comparisons among future economic evidence.