Fully integrating sustainability into a corporate strategy has progressively become the ubiquitous norm. However, designing a credible, effective sustainability strategy still appears to be a challenging task and lacking employee support frequently labels the strategies as insignificant public relations practices. As the awareness for sustainability issues prevails, the call for a substantial paradigm shift in corporate mindsets emerges: For any sustainability strategy to be successful, the affected employees need to be aligned and engaged behind it. Human Resource Development (HRD) as proper training enabler for such strategies offers important voice and expertise to realize the true satisfaction of sustainability ambitions. At the present time of globalization and due to the critical need to consider environmental, social, and financial consequences of business operations, the sustainability movement cannot be considered a passing trend. Since HRD is expected to play a facilitative role in establishing corporate sustainability, this work proposes theoretical approaches linking HRD with sustainability and corporate responsibility. The empirical purpose of this study is to investigate the current engagement of HRD in the field, examining one fundamental question: Assuming that employees are key success factors for sustainability strategies, how can HRD professionals and departments ensure that sustainable behavior will be part of all members of a company? Drawing from qualitative expert interviews with senior HRD managers of large companies that declare explicit commitment to sustainability within different industries, the evidence shows that their engagement still tends to be limited. This research concludes with an argument for greater involvement of HRD in corporate sustainability endeavors and offers suggestions for research and practice towards this end.