An urgent issue for new ventures is how firms can effectively use human resource policies to promote growth and employee productivity. In this study, we propose a model of how three motivation-enhancing human resource (MHR) practices relate to firms’ subsequent growth and productivity. In addition, we demonstrate how two temporal factors influence the relationship of MHR practices with subsequent growth and productivity. Specifically, we assess how the initial implementation of MHR practices creates short-term costs and long-term benefits, and we assess how firm developmental stage influences the relationship of MHR practices with subsequent growth and productivity. We test our model by using random coefficient growth modeling with a sample of 677 firms tracked for 6 years. We found that MHR practices are related to subsequent firm growth and productivity. In addition, we show that the initial use of MHR practices creates inefficiencies that, in the short-term, slow growth and productivity but have positive long-term effects of subsequent growth and productivity. Finally, we show that the relationships of MHR practices with growth and productivity are much stronger when firms are in a postrevenue, growth goal stage. We conclude with a research agenda and recommendations for how new ventures can make effective use of MHR practices to promote performance.