The present study uses theory of planned behaviour (TPB) and social cognitive theory (SCT) to examine the eco-friendly purchase intentions of individuals. This study also examines the role of knowledge as a predictor and as a moderator in the theories inspected for determining individual's eco-friendly purchase intention. Data is collected in India using a survey method from 456 respondents. AMOS 25.0 and SPSS 16.0 is used to anlayse the data to ensure reliability, validity, and model fit, and to compare the theories. The results of the study indicate that TPB is a better predictor of eco-friendly purchasing intentions than SCT. Additionally, knowledge significantly influenced eco-friendly purchase intentions directly (i.e., as an extension variable in both theories) but failed as a moderator to significantly influence the relationships in the theories. These results provide empirical guidelines to policymakers and practitioners for promoting eco-friendly products. Finally, future directions for taking this research forward are discussed.