Digital technologies have facilitated access to instructional multimedia materials, and a large body of literature has shown that these technologies can support students' learning. However, recent research also shows that many teachers have misconceptions about learning from multimedia materials. Further, numerous studies point out that numerous factors account for the successful use of technologies in class. Based on data from a large-scale study with upper secondary school teachers (n = 2247), we analyzed what predicted teachers' creation of digital multimedia, to determine whether it was solely technology related factors derived from the will-skill-tool pedagogy model, or also factors related to teachers' alignment with well-established design and processing principles of multimedia learning. Overall, a third of the respondents were fully aligned with the multimedia principles, and another third with all but the coherence principle. We investigated how this alignment affects the creation of multimedia learning material. Multilevel linear modeling analysis (MLM) indicates that of all multimedia principles, only the dual coding assumption has a significant and positive impact on teachers' frequency of multimedia document creation. In addition, teachers' positive beliefs about technology use in class, their self-reported technological knowledge (skill) and their self-reported knowledge in teaching with digital technologies significantly and positively predict how often they create digital multimedia documents. These results stress that, for now, teachers rely more on their technological beliefs and self-reported knowledge to integrate digital tools in their lesson than on their alignment with multimedia design guidelines. As previous studies show that available digital instructional multimedia do not always follow multimedia learning principles, this could lead teachers to create or use inappropriate digital multimedia materials.