For more than 20 years, the 50 agricultural mechanics laboratory management competencies identified by Johnson and Schumacher in 1989 have served as the basis for numerous needs assessments of secondary agriculture teachers. This study reevaluated Johnson and Schumacher's instrument, as modified by Saucier, Schumacher, Funkenbusch, Terry, and Johnson (2008), to reduce the number of competencies and update the constructs of agricultural mechanics laboratory management competencies through factor-analytic and psychometric analyses. Five-hundred and three in-service secondary agriculture teachers from six states, surveyed between the spring of 2008 and the spring of 2010, served as the population for this study. As a result, the 70 agricultural mechanics laboratory management competencies included in the instrument modified by Saucier et al. (2008) were reduced to 33 competencies, in eight constructs. A further outcome was reflected in the psychometric evaluation of the eight constructs, which resulted in acceptable internal consistency reliabilities that ranged from 0.82 to 0.96. Multi-state benchmarks for agricultural mechanics laboratory management abilities of secondary agriculture teachers were also proposed. The results further indicated that the revised constructs were appropriate to assess agricultural mechanics laboratory management competencies across Huberman's (1989) five teacher career stages. (Contains 7 tables.)