["Review of Income and Wealth, Volume 72, Issue 2, May 2026. ", "\nABSTRACT\nCapital is notoriously heterogeneous, including physical, intangible, human and natural capitals, and this heterogeneity can make measurement very difficult. To bring structure to the wide range of capital assets, and inform measurement, we define five dimensions for classifying capital types: produced versus non‐produced; fixed versus non‐fixed; tangible versus intangible; standardized versus non‐standardized; and exclusive versus non‐exclusive. By cross‐classifying these dimensions, we identify a range of capital types and draw lessons for measurement methodology. We find that assets are less difficult to measure when they are standardized and exclusive while non‐standardized assets are hard to measure due to a lack of comparators and non‐exclusive assets are hard to value since the market value does not include all its social value. We then suggest possible measurement strategies for the harder‐to‐measure capital types.\n"]