When writers mine information from multiple sources to develop an essay, they reinterpret and reorganize their knowledge as they pursue and, possibly, reshape goals for rhetorical structure. Such writing tasks are popular across age levels and domains. It is assumed cognitive processes engaged in this kind of task provide practice that improves writing skills and deepens engagement with content. However, writing grounded in multiple and typically diverse sources is a demanding task. Successfully synthesizing information across multiple sources calls on multiple and interwoven cognitive and metacognitive processes as authors balance work in rhetorical, content and metacognitive spaces. To successfully traverse this complex and evolving cognitive landscape shaped by multidimensional goals, writers need procedural knowledge that operationalizes skills plus broad conditional knowledge to guide using those skills. For these reasons, success in multi-source writing tasks requires extensive and productive self-regulation. To advance research on these issues and give direction to engineering writing analytics to support productive self-regulation in multi-source writing, we synthesized research accessing and synthesizing content across multiple sources (Cho et al., Strategic processing in accessing, comprehending, and using multiple sources online. In: Handbook of multiple source use. Routledge, pp 133–150, 2018; Perfetti et al., Toward a theory of documents representation. In: The construction of mental representations during reading. Psychology Press, p 88108, 1999; Rouet et al., Educ Psychol 52(3):200–215, 2017; Rouet and Britt, Relevance processes in multiple document comprehension. In: Text relevance and learning from text. Information Age Publishing, Inc., pp 19–52, 2011), writing processes (Bereiter and Scardamalia, The psychology of written composition. Hillsdale, 1987) and self-regulated learning (SRL; Winne, Cognition and metacognition within self-regulated learning. In: Schunk D, Greene J (eds) Handbook of self-regulation of learning and performance, 2nd edn. Routledge, pp 36–48, 2018; Winne and Hadwin, Studying as self-regulated learning. In: Hacker DJ, Dunlosky J, Graesser A (eds) Metacognition in educational theory and practice, Erlbaum, pp 277–304, 1998). The result is a two-dimensional typology of cognitive and metacognitive processes in self-regulated writing using multiple sources (SR-WMS) spanning two problem spaces in writing tasks, rhetorical and content.KeywordsSelf-regulationMulti-source writingMultiple source comprehensionnStudyLearning analytics