This original article investigates the influence of behaviors associated with effectuation and causation on the sustainability orientation in entrepreneurial ventures. Based on a quantitative survey among 140 sustainable ventures, we find support for the hypothesis that causal behaviors reinforce sustainability orientation. Surprisingly, we realize that effectual behaviors exert a positive influence on sustainability orientation as well, although we hypothesize the opposite effect. These results may instruct sustainable entrepreneurs, researchers, and educators to purposefully include both behaviors in the venture development process, and they highlight that causal and effectual behaviors are both important elements for teaching sustainable entrepreneurship in advanced settings.