Technology-supported social networks have been penetrating many aspects of our lives from friendships/blogging sites to working organizations. Particularly, individuals as employees of companies have started to adopt a sort of organizational knowledge based on their operational technologies. This paper, so, focuses on a special type of organizational social network knowledge acquired from deploying workflow technologies, which is dubbed 'activity-performer affiliation knowledge.' That is, the paper theoretically derives a series of concepts and algorithms not only for representing and discovering the knowledge but also for analyzing the discovered knowledge. These theoretical concepts and related algorithms are based upon the methodology of information control net workflow models, and the discovered knowledge eventually represents involvements and participation relationships between a group of performers and a group of activities in workflow models. Finally, we summarily describe the implications of the activity-performer affiliation knowledge, and how much it is worth discovering them in workflowdriven organizations and enterprises producing massively parallel interactions and largescaled operational data collections.