This paper examines digital and mobile learning that goes beyond bounded communities and closed domains. While recent work from the field of mobile learning has emphasized the importance of learning across "contexts," little analytical attention has been paid to the underlying dynamics of this phenomenon. To illuminate this, the four learning mechanisms of identification, coordination, reflection and transformation from the framework of boundary crossing are linked with mobile learning practices. It is argued that mobile phones and specifically mobile social media serve as boundary crossing tools: tools that are used by learners to generate multimodal representations that reflect their experiences and identities, and to share them across their digital and non-digital social networks. The four learning mechanisms are facilitated by the learners' engagement with more heterogeneous and peripheral spaces of their social networks in ways not previously possible.