In recent years companies have begun to implement a  series of human resource management (HRM) practices that are referred to in the  literature as high-performance or high-commitment. Among others these practices  include employee involvement, training and organisational incentive plans. In  this study we attempt to determine how and to what extent the adoption of this  type of practices affects the firm's performance record. We focus specifically  on the impact HRM has on operational performance. Moreover, we test if the  impact of high-commitment practices on firm performance is contingent on the  strategy followed by the firm. We try to detect possible differences in the  relationship between HRM and the different kinds of operational results  (efficiency, quality, and time). For this aim we use a database covering an  initial sample of 965 factories each with a workforce of over 50 employees. We  begin with a review of the literature before going on to present the descriptive  statistics for the variables to be used and, finally, testing the relationship  between HRM and operational performance through the estimation of several  ordered probit models. Our results reveal the presence of a positive,  statistically significant correlation between the adoption of high-commitment  practices and improvements in quality and time-based performance. We also find  that this effect is universal and not dependent on the strategy used by the  firm.