PurposeThe purpose of this paper is to examine the effectiveness of social media guidelines (SMGs), as well as their impact on control mutuality, a sub-dimension of the organization–employee relationship (OER). A total of two studies compare guidelines with a focus that is either predominantly incentive or restrictive. In addition, they investigate the moderating effect of guideline writing style and enforcement.Design/methodology/approachIn total, two online experiments were conducted among Belgian employees. Participants read a social media policy manipulated in terms of focus (restrictive vs incentive) and style (conversational vs corporate; Study 1) or enforcement (signature requested vs not requested; Study 2).FindingsIncentive guidelines increase employee branding behavior more than their restrictive counterparts, while also safeguarding employees' perceived control mutuality. However, solid SMGs will not compensate for an organization's bad reputation among employees. The guidelines' style and manner of enforcement did not seem to matter.Practical implicationsCommunication executives can use our findings to draft SMGs in a way that increases opportunities (e.g. ambassadorship) and reduces risks (e.g. criticism) associated with employee social media use.Originality/valuePrior research on SMGs is predominantly descriptive and focused on the organizational perspective. This research paper contributes to both theory and practice by studying the causal impact of these guidelines on employees.