Global warming and the depletion of natural resources have motivated calls for significant changes in the way organisations produce and deliver products and services. In many countries, mandatory measures, such as carbon taxation, have been introduced to stimulate the greening of supply chains. However, research on the impact of the implementation of green supply chain management (GSCM) practices on corporate performance is still inconclusive. This study investigates the relationship between GSCM practices and corporate performance using a sequential mixed methods research design. First, a quantitative survey was conducted with 140 respondents to test a series of hypotheses. When several of these hypotheses were not supported, a qualitative approach was introduced to uncover the barriers to corporate performance improvements. The qualitative study found some key reasons for why GSCM practices failed to impact many of the dimensions of corporate performance. The majority of these reasons related to issues in implementation, including eco-design, green purchasing, environmental co-operation and reverse logistics. This information allowed us to develop a series of managerial recommendations for firms interested in improving their performance by implementing GSCM practices. We found that quantitative research alone was not sufficient to uncover the links between GCSM practices and corporate performance, which highlights the need to supplement quantitative methods with qualitative research in order to explain the underlying reasons to support or not support various GCSM practices.