ENThis study explores the links between environmental attitudes and values, personal norms, perceived responsibility, pro-environmental and prosocial engagement in sustainable consumption, and sustainable consumption behavior. Data was collected by surveying 904 Lithuanians through non-random quota sampling. Empirical research reveals that internal factors, such as environmental attitudes, values, personal norms, and perceived responsibility, have a positive direct effect on engagement with sustainable consumption. In addition, the findings indicate that pro-environmental and prosocial engagement to act as a mediator in enhancing the impact on sustainable consumer behavior. The results of this study expand the understanding of the engagement phenomena and how it can assist in shifting to sustainable consumer behavior in the Lithuanian context. Opportunities to encourage sustainable consumption behavior are presented for marketers and policy makers. Keywords: environmental attitudes; environmental knowledge; personal norms; perceived responsibility; pro-environmental and prosocial engagement in sustainable consumption and sustainable consumption behavior. [From the publication]