Electronic networks of practice are computer-mediated social spaces in which individuals working on similar problems self-organize to help each other and share perspectives. Based on previous research positing that the interaction created by network participants produces an online public good of knowledge, the purpose of this empirical paper is to use theories of public goods and collective action to investigate this provision of knowledge. While based on the same technology platform and a similar concept, we examine three cases in different professions: education, healthcare, and tourism by examining how the 1) heterogeneity of the individuals, 2) relational structure of social ties, 3) norms of behavior, 4) affective factors, and 5) sanctions for noncompliance impact the creation of a public good. We find that the most successful effort to create an electronic network of practice was within education and that one contributing factor was the site's ability to leverage existing offline networks of practice to create a relational structure of stronger social ties between members. In summary, these results reveal that taking a unitary view of the underlying collective masks possible heterogeneity along a number of important dimensions and as a result may undermine the likelihood that the public good is created and maintained.