High-performance work practices (HPWP) have been found to increase financial performance. Institutional theory suggests that this effect may be moderated by labor market institutions, such as labor market flexibility and labor market efficiency. We explore this relationship using a combined data set comprised of data on HPWP from ASSET4, financial and other company-level data from the Worldscope Database, and national institutional context data from the World Economic Forum’s Global Competitiveness Report. With an international sample of roughly 20,000 archival firm-year observations across a seven-year period, we use pooled OLS regression models with robust standard errors, clustered at the firm level. We find support for all predicted relationships except for a direct relationship between labor market flexibility and performance: Strong formal institutional pressure (low labor market flexibility) increases the positive financial impact of HPWP. Strong informal institutional pressure (high labor market efficiency) affects the financial performance of businesses directly and positively, and also indirectly by increasing the positive effect of HPWP on financial performance. We conclude that companies seeking the most financially-rewarding approach to human resource management (HRM) should engage in HPWP, encourage the local population to expect and value such practices (e.g., by promoting women’s rights), and, counterintuitively, encourage more government regulation of business around HRM practices.