Based on a sustainability perspective we offer a research framework that allows discussion of the relationship between positive and negative effects of flexible HRM. Sustainability, as an umbrella concept, aims to integrate three perspectives: economy, ecology and society. The relationships between these perspectives are characterized by paradoxical tensions. Following Ehnerts' approach of 'Sustainable HRM', we use coping strategies from paradox theory in order to discuss paradoxical tensions within research findings on flexible HRM. We conclude that the adapted usage of Sustainable HRM offers a starting point for more sophisticated research into the relationship between the positive and negative effects of flexible HRM.