Businesses of every type have joined the digital world through the web-log, more commonly known as the blog – a novel and changing form of corporate communication that resides in an unsettled legal world. These business or corporate blogs come in different varieties. Some appear to be written by chief executive officers or other high-ranking executives. Some purport to be written by employees with a particular expertise. Some are directly supported, even hosted on the web, by the corporation. Some claim to be independent of any corporate influence, control or editing. Some are simply silent on those questions. Businesses and public relations professionals cannot safely treat any of these blogs as fully-protected First Amendment speech. Without a specific analysis of the form and content of each, neither the corporate subjects nor the bloggers can assume legal responsibility or protection. Public relations professionals, bloggers and businesses should be guided by established principles of agency law and other fields (including defamation law, for example), but should also pay close attention to Section 230 of Communications Decency Act of 1996. This study examines the legal issues stemming from the current cases, analyzes the impact on corporate and public relations blogging, and suggests a methodology for classifying various blogs and evaluating the risks presented by each.