This chapter focuses on quantitative content analysis of online interactions, in particular, asynchronous online discussion. It clarifies the definitions of quantitative content analysis and provides a summary of 23 existing coding schemes, broadly categorized by the theoretical constructs under investigation: (1) (Meta) cognition, (2) knowledge construction, and (3) presence. To help interested researchers harvest the rich source of data in online communities, guidelines for using quantitative content analysis of online interactions were provided. In addition, important methodological considerations and issues were discussed, including the issues of validity, reliability, choice of unit of analysis, and latent versus manifested content.