The modern workplace requires a complex set of competencies, often termed transversal skills, which transcend knowledge-based skills. The assessment of transversal skills has become a particularly pertinent issue in educational and workplace settings as these skills can be difficult to measure and often require more authentic performance-based tasks than traditional paper-based tests. The research conducted for this PhD study focuses on the assessment of Ability Emotional Intelligence (AEI) through Collaborative Problem Solving (CPS) contexts. AEI is an individual’s ability to understand, use and manage their emotions to solve problems in everyday life (Mayer, Caruso & Salovey, 2016). Similar to other intelligence theories, it is proposed that it develops over a lifetime and can be improved with practice and instruction. Those with well-developed AEI tend to have high quality social interactions, are more competent collaborators and better communicators. The present research explored the types of emotional abilities that are observable and assessable when children were working on CPS tasks involving Lego Spike Prime Education materials. Using a qualitative case study design, 26 primary school students between 10 and 12 years of age were video recorded in a classroom in Ireland as they worked collaboratively on completing the Lego tasks. Findings indicate that although AEI can be observed and assessed while working on CPS tasks, group dynamics can impact the types of abilities that can be observed. The outcomes of this study will help to inform future assessment research in the area, as well as assisting educators in developing the transversal skills needed to support learning during the primary school years. Study outcomes will also have implications for the assessment of AEI beyond primary education and in contexts beyond formal education.