This chapter addresses the increasingly important issue of how the National Labor Relations Act applies to postings by employees on social media. It argues that in large part the National Labor Relations Board (“Board”) has correctly applied the decades-old concept of protected concerted activity to new technological meeting places. The legal concepts at issue are founded in longstanding precedent. The chapter discusses the laws protecting employee posts on social media that are concerted activity for mutual aid or protection. The chapter demonstrates that employers are prohibited from disciplining employees for use of social media in precisely the same way they are prohibited from disciplining employees for other protected concerted activity. The chapter also discusses the Board’s regulation of employers’ social media policies. The Board regulates the policies to insure they are not so broad as to interfere with employees’ exercise of their right to engage in protected concerted activity. The chapter demonstrates that, for many years, employers and employees have successfully complied with regulation of similar employer policies, and the result should be no different as to social media policies. Other authors have argued that the Board precedent is inconsistent, confusing, or wrong, and proposed legal refinements, rulemaking, or legislative action. This chapter updates the developing law and instead contends that the current Board precedent is largely correct, and that only a few small changes would place it on extremely solid footing.