This study explores the antecedents of high-performance work systems (HPWS) and the consequences of HPWS adoption by juxtaposing external (i.e., institutional pressure) and internal (i.e., resource constraints and strategic goals) environmental factors. Although prior research has suggested that focal firms’ internal and external factors, separately, may influence their decision-making in adopting HPWS as well as the consequences of their decisions, I propose that the juxtaposition of internal and external factors helps researchers gain a fine-grained understanding of the competing goals of the focal firms. Drawing on insights from the institutional theory and contingency theory, I argue that although firms universally experience industry peers’ HPWS use as a key external factor, focal firms’ firm age and market entry timing may serve as the key internal factors that create variations in their decisions to adopt HPWS and consequences. Using nationally representative longitudinal data on 3,317 firm-year observations from seven waves of data between 2005 and 2017, I find that firms of different ages (i.e., new vs. established firms) and market entry timing groups (i.e., first-movers vs. late-movers) are motivated differently when their industry peers increase or decrease the use of HPWS. Also, I find that the performance consequences of a focal firm’s HPWS adoption decisions are a function of whether the firm is a first-mover or a late-mover, in combination with the level of its industry peers’ HPWS use.