Social-emotional competencies - such as self-control, perseverance, or empathy - are a basic requirement for a happy and fulfilling life. This has been increasingly recognised by researchers, national governments including the UK and US, as well as international organisations such as OECD. This PhD research investigates the potential of technology in supporting development of such social-emotional competencies. The HCI research on this topic has been limited so far and only very little is known about what are the key challenges involved in developing SE competencies, if and how technology could meaningfully help address these, and what would be the underlying learning mechanisms guiding development of such systems. In contrast, a burgeoning body of literature in Prevention Science and Educational Psychology is concerned with the psychological mechanisms underpinning the development of SE competencies. To understand the opportunity for technology at the intersection of these fields, the presented research is grounded in two long-term case studies of existing SE programs: - universal prevention programs in primary schools, where the students are taught basic life skills, such as self-awareness, self-regulation or relationship skills; and - masters counselling course, where the future therapists are going through an indepth, sophisticated training aimed to develop expert social-emotional competencies. By investigating and developing technologies across two such diametrically different contexts in terms of student capabilities and the depth of SE competencies targeted, I aimed to understand what might be common challenges and mechanisms that are transferable across SEL contexts. The thesis research contributes to the knowledge in HCI on two interrelated levels: First, it provides an in-depth understanding of the two learning contexts including in-the-wild deployments of proof-of-concept systems bringing the novel focus on facilitating socialemotional learning. Second, it draws out a conceptual framework that suggests potential strategies to designing SEL support systems more broadly. The basis for this framework is Schön's notion of reflective practicum, which is used as a sensitising concept to highlight the shared strategies and curricular components underpinning learning across the two contexts.