Two developments in the last two decades frame the importance of Web-based marketing communications for firms. First is the phenomenal growth of the Internet as a viable commerce and communication option and second is the clear shift in attitude research toward recognizing the pervasive role of automatic processes in almost all the social psychological processes. Therefore, this article discusses the potential implications of Web-based marketing communications for consumers' implicit and explicit attitudes. In doing so, first, this article reviews the emergence of research on implicit attitudes, distinguishes implicit attitudes from explicit attitudes, and discusses research on explicit and implicit attitudes relative to branding. Second, a brief discussion of marketing research on attitude is provided. Third, five empirically testable research propositions are developed and presented. Finally, given the potential implications for research and practice, the article concludes with a call for research. ©2010 Wiley Periodicals, Inc.