This chapter explores the integration of competencies and affect in designing holistic summative assessments in integrated STEM education. By drawing on a theoretical framework that incorporates cognitive aspects of learning and affect theory, the goal is to establish a comprehensive perspective on STEM competencies in summative assessment, introducing the concept of affect-sensitive learning. A case from the LabSTEM+ project is used to emphasize the importance of considering affect, not only in STEM teaching, but also in STEM assessments. Our research questions delve into the role of affect in analyzing summative assessment, assessing students’ STEM competencies and their affective experiences related to a STEM assessment. The analysis of the case study reveals a dynamic interplay between STEM competencies, and the affective domain. Students actively engage with the learning environment through materials, such as pipes and water, demonstrating subject-oriented and STEM competencies including problem-solving, modeling, and communication. The learning environment and these materials enhance affective experiences, fostering motivation, interest, and autonomy. This study contributes to a deeper understanding of the role of affect in STEM education assessment and highlights the importance of integrating affective aspects to promote a more holistic approach to learning and assessing STEM competencies.