Several indicators are used in the literature to measure part-time farming. None of these studies, however, examine the comparability of the indicators ' measurements and how this interchangeability may vary by year and place. Using data from the 1987, 1992, and 1997 Census of Agriculture for U. S. counties, 1 investigate the interchangeability of three part-time farming indicators -days wo^ d off-farm, principal occupation, and market value of sales -within and across subpopulations and time periods. Results show that although there are a few differences in the measurements produced by these indicators, similarities in measurements exist across most locales and time periods.