Social media platforms play important roles in many educators' lives. In particular, teacher professional activities on Twitter have received attention from scholars. However, research has not typically explored Twitter use with attention to the diverse national contexts in which teachers work. To address this literature gap, the present qualitative study collected interview data from teachers (N=29) in England, Norway, and the United States of America. Inductive data analysis yielded findings related to teacher purposes for, changes in, and benefits and challenges of Twitter use. Both similarities and differences in Twitter use were noted across participants from the three national settings. We discuss these findings in relation to literature, theory, and practice around teacher professional learning in a digital era.