Building on the stimulus-organism-response model, this paper aims to fill the considerable research gap by developing a deeper understanding of social commerce as a global emerging phenomenon and investigating the effectiveness of social commerce marketing stimuli and its consequences on consumer behavior on Instagram. The study adopts a mixed-methodology approach, including a web-based survey and a focus group interview, to build a deeper understanding of the phenomenon and account for the social aspects of social commerce. Based on a sample of 317 international consumers, the analysis demonstrates that all dimensions of social commerce marketing stimuli have significant effects on online brand engagement on Instagram; which consequently positively influences brand trust and online purchase intention. Moreover, the focus group interview complements the findings and provides potential explanations for the discovered relationships.