Even with proven benefits of engaging in sustainability, and stakeholder and regulatory pressure to do so, small- and medium-sized enterprises (SMEs) seldom adopt environmental practices beyond those required. To investigate why some SMEs adopt environmental practices while others do not, we studied the proactive orientation–environmental practices link and the moderation of regulatory pressure on this relationship. Based on a survey of 286 SMEs in the wine industry in Italy, France, Denmark, and the United States, we tested our model using regression analysis. We found support for our hypotheses on the positive proactive orientation-environmental practices link and the enhancing role of regulatory pressure. We conducted further supplementary exploratory analyses to examine these relationships among different types of environmental practices. The findings from our study offer new research directions regarding the nuanced roles of proactive orientation and regulatory pressure in motivating SMEs to adopt more environmental practices.