While prior research suggests that many educators turn to social media to grow and enhance professional learning networks (PLNs) that extend beyond their schools, little is known about how PLNs shift over time. In this exploratory study, we investigated the nature of continuity and change in the PLNs of 192 K-12 and university educators from 17 countries. Participants responded to our request to comment on PLN descriptions they provided in a previous 2014 survey, and then identify continuity and change during the intervening years. Respondents overwhelmingly expressed that their PLNs had changed over the four years between the two surveys. The causes of PLN changes appeared to be diverse, dynamic, and interrelated. Various proximal and distal factors contributed to changes in professional activities. We frame the study through social ecological systems theory, discuss the significance of these findings, and consider implications for K-12 and higher education professional learning. Educators and those who lead and support their professional learning should reflect upon and attend to PLN change to ensure more educative results for teachers and students.