Companies view social commerce (s-commerce) as an additional online marketing sales channel of which the revenue-generating potential has substantially increased through the recent introduction of online payments within these channels in Russia. This paper examines which factors influence the consumer buying decision through s-commerce channels in Moscow. Through a rigorous process of expert interviews, we gain a first insight into the s-commerce market in Russia. Following this preliminary qualitative analysis, we collect survey data on purchase decisions among buyers on social media (stage 1: 303 respondents; stage 2: 252 respondents). An in-depth analysis via structural equation modelling reveals numerous factors that positively contribute to purchase intention. Among others, we find that the intensity of social interaction (e.g. frequency of updates and response time), quality of service (e.g. payment and delivery) and the availability of positive reviews are statistically significant determinants for a purchase decision. However, in line with expert feedback, we find that the significant influential factors differ across s-commerce channels. For example, in Инстаграм companies should emphasize platform convenience, content personalization and trust, with the latter factor significantly depending on security and the availability of reviews.