Research shows that family firm governance can provide performance advantages, but the question of whether such performance advantages are sustainable over time has been overlooked. Extending resource-based theory with insights concerning family firm governance as an isolating mechanism, we hypothesize that family firms are more likely to sustain superior performance than non-family firms. We also hypothesize that family firms’ ability to sustain superior performance is lower in innovation-intensive industries and higher in capital-intensive industries. A longitudinal analysis of S&P 1500 manufacturing firms from 1996 to 2013 support our hypotheses, highlighting a new method for assessing resource inimitability and non-substitutability and advancing knowledge about the relationships between family firm governance and performance over time and across different competitive environments.