The purpose of the study was to explore the phenomenon of K-12 educators using Twitter to support their informal professional learning. The research used a case study design with both qualitative and quantitative data sources. Data were collected using three procedures: an adapted version of the Constructivist On-Line Learning Environment Survey (COLLES) (Taylor & Maor, 2000a, 2000b), semi-structured interviews and online Twitter content. The findings demonstrated that Twitter was used to complement professional learning by accessing and sharing information, as a catalyst for learning beyond Twitter and for collaborative dialogue and discourse. Further, the findings indicated the reason educators used Twitter was to experience professional learning that was personalized and relevant, through access to information and resources while also establishing and developing connections to others. Such learning opportunities occurred through various interactions that built and supported learning networks while allowing educators to participate to varying degrees.