This research was prompted by the search for a fundamental theory for human resource management (HRM) after 30 years of existence. Applying first generation meta-analysis, the research aimed at identifying missing links in Jiang et al.’s (2012) A-M-O model. Thirty hypotheses were developed that focused on variables of HRM single practices in the A-M-O strategic bundles and made predictions about how they associate with various organizational outcomes. Data were collected at organizational level from 151 primary studies from 1985 to 2015, which extended Jiang et al.’s (2012) collection by 36 primary studies. The comprehensive meta-analysis results showed that there were seven missing links in Jiang et al.’s (2012) model and a correlation analysis showed that the three domains of HRM practices – ability-enhancing, motivation-enhancing and opportunity-enhancing – had both direct and indirect significant associations with various organizational outcomes. The significant links completed Jiang et al.’s (2012) model and a new model was proposed for further research that will confirm an acceptable model and theory for HRM. The theoretical and practical contributions of the study are well discussed for research and management practices.