This Note examines how architecture, and particularly the design and coding of software on the Internet, helps shape social norms. The Note makes two points about architecture and norms. First, architectural decisions affect what norms evolve and how they evolve. By allowing or facilitating certain types of behavior and preventing others, architecture can promote the growth of norms. On the flip side, architecture not tailored to promote certain positive norms of cooperation or compliance with the wishes of the designer (or in some cases the law) may allow the growth of antisocial norms. Second, because design decisions affect behavior directly as well as indirectly through norms, software engineers must recognize the regulatory function of the code they create. Although online architecture can promote productive social norms, design decisions can also create a backlash by fostering the development of norms that work against the sort of behavior the code is written to promote. The Note begins by describing how architecture works to regulate behavior in the physical world, examines the leading theories of social norm development, and explores the intersection of architecture and norms. The latter part of the Note transposes the general theory of architecture and norms to the Internet world, first describing the particular features of the Internet—anonymity, dispersion, and the free flow of information—that make the process of norm development different in cyberspace than in physical space, and then turning to two examples, online auctions and digital music, to show how software engineers have effectively and ineffectively used code to promote the development of social norms.