Membership in social networking sites is increasing rapidly. Social networking sites serve many purposes including networking, communication, recruitment, and sharing knowledge. Social networking sites, public or private, may be hosted on applications such as Facebook and LinkedIn. As individuals begin to follow and participate in social networking sites of interest, is it possible that virtual communities of practice (VCoP) will form? In VCoPs, knowledge sharing, learning, and problem-solving practices occur. Using the Trainers Network, a group on the social networking site LinkedIn, this mixed methods study quantitatively examined the relationship between connectedness and learning. Connectedness and learning are important factors in creating a sense of community. Learning and trust may develop when community exists and is essential in sustaining VCoPs. The study qualitatively explored the perceived transfer of informal learning from the social networking site to workplace practices and professional development. The implications for workplace learning and performance professionals are numerous for social networking sites that offer the benefits of VCoPs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]