["Business Strategy and the Environment, EarlyView. ", "\nABSTRACT\nThis study investigates how board‐level motivation toward success and achievement (MSA) shapes corporate sustainability strategy. We construct the board‐level MSA measure by averaging the Hofstede MSA scores of each director's nationality or birth country. Using 17,105 firm‐year observations from 3998 firms across 43 countries over 2007–2022, we report three sets of findings. First, board‐level MSA is negatively associated with ESG performance. Moreover, board‐level MSA has stronger explanatory power than country‐level MSA, indicating that within‐board heterogeneity captures variations beyond static national proxies at the firm level. Second, the negative effect of board‐level MSA attenuates over time. Firms with high‐MSA boards improve their ESG performance more slowly than low‐MSA peers. Third, the board‐level MSA‐ESG relationship is conditional on financial performance. High‐MSA boards prioritize financial success, but once financial targets are met, accumulated organizational slack enables ESG engagement, reversing the otherwise negative effect and reflecting a slack‐resources logic rather than a permanent trade‐off. This conditional logic gives rise to a U‐shaped pattern where ESG performance is lowest at moderate MSA levels, and the negative effect reverses at higher levels where financial slack has accumulated. Overall, our analysis shifts cultural analysis from the country to the board level and identifies time and financial performance as key boundary conditions. The documented U‐shaped pattern refines the slack resources hypothesis, reconciling trade‐off and slack resources perspectives in the corporate sustainability literature.\n"]