Sustainable development is gaining recognition as a sub-domain of entrepreneurship and recent research has suggested that sustainable entrepreneurship may be the most important topic of our time. The majority of the existing research focuses on theory building and qualitative case studies of new ventures. While commendable, this research leaves a gap in our understanding about the attitudes existing entrepreneurs possess regarding sustainability. This study develops a measure of environmental sustainability orientation (ESO) to examine the impact of gender, and self-identity (SI) on the sustainability orientation of existing entrepreneurs. We explore questions regarding 1) gender differences in ESO, 2) the relationship between SI and ESO, 3) how gender moderates the SI-ESO relationship, and 4) if age of the venture relates to ESO.