This research examines how national institutions: formal (e.g., labor laws) and informal (e.g., cultural norms), shape the adoption and impact of managerial practices across countries. It explores how practices like flexible work, talent management, and selection affect outcomes such as absenteeism, turnover, and profit. Using large-scale cross-national data and multi-level modeling, the work advances theory on the interplay between global HRM and local contexts.