The importance of fostering and measuring non-cognitive skills, commonly viewed as critical personal attributes necessary for success in classroom, labor market, and life in general, has been widely recognized. However, despite technological advances and emergence of learning analytics as a multidisciplinary research field, the development of non-cognitive skills assessments remains rather limited. Existing research and practice of online learning, focuses primarily on advancing and automating methods of cognitive skills assessments, whereas non-cognitive skills assessments, on the other hand, traditionally rely on self-reported surveys with limited response rates and questionable validity and reliability. This workshop aims at bridging the scarcity of scalable non-cognitive skills assessments in digital educational environments for learning at scale. We start by reviewing different approaches to the non-cognitive skills assessment in various educational contexts, ranging from traditional face-to-face to online learning settings. Further, by leveraging theoretical and technological advances, we discuss the potential for developing innovative methods that would enable assessment of non-cognitive skills in online learning environments with particular focus on learning at scale.