As the volume of consumer-brand interactions is increasing in the social media setting, it becomes essential to understand how to foster relationships to create favorable attitudes towards the brand, stimulate sales, and enable consumers to forward the brand name to others. In this regard, this research focuses on the effect of communication style (formal vs. informal) that should be used for products that have different levels of self-expression (high vs. low) in social media communications. An experiment was conducted with 384 participants. The results indicated that consumers prefer informal communication regardless of the self-expression level of the product in social media. Investigating the interaction effects, the authors demonstrated that highly self-expressive products favorably stimulate word-of-mouth intention in case of formal communication. However, it is the informal communication that stimulates purchase and word-of-mouth intentions and brand attitudes when the product is low self-expressive in nature.