► Knowledge management as IS implementations that enable knowledge processes. ► Knowledge management builds protective capabilities in firms. ► Knowledge management evolves through the increasing use of social software. ► New strategic research agenda on knowledge management by social software. Knowledge management is commonly understood as IS implementations that enable processes of knowledge creation, sharing, and capture. Knowledge management at the firm level is changing rapidly. Previous approaches included centrally managed, proprietary knowledge repositories, often involving structured and controlled search and access. Today the trend is toward knowledge management by social software, which provides open and inexpensive alternatives to traditional implementations. While social software carries great promise for knowledge management, this also raises fundamental questions about the very essence and value of firm knowledge, the possibility for knowledge protection, firm boundaries, and the sources of competitive advantage. I draft a strategic research agenda consisting of five fundamental issues that should reinvigorate research in knowledge management.