Although physical education (PE) teachers have increased access to digital/online continuous professional development activities, there are few robust accounts of how they engage with and experience these environments. Purpose: The purpose of this study was to examine PE teachers' participation patterns within self-directed online PE continuous professional development activities using mobile instant messenger. Methods: Data were generated from (a) 5,246 messages exchanged in the mobile instant messenger chatroom from 281 teachers, (b) semistructured interviews with 10 teachers, and (c) 1,275 messages posted by the 10 interviewed teachers. Quantitative data were analyzed for measures of central tendency, and qualitative data were analyzed inductively. Findings: Five patterns of PE teachers' usage of mobile instant messenger were identified: (a) ringmasters, (b) passive uploaders, (c) active uploaders, (d) requesters, and (e) bystanders. Discussion: The findings suggest that each engagement pattern illustrates the differential goals of learning, types of interaction, and forms of participation by teachers engaged in online continuous professional development.