The two key purposes of assessment, formative and summative, often contradict each other when attempted used simultaneously. Summative assessment of learning will generally prevent formative assessment for learning. Moreover, in order to be useful and manageable, the assessment method must be easy to integrate into and should ordinary teaching. This study explores how such an assessment method, called the Structured Assessment Dialogue (SAD), could be designed and the rationale behind it. Then the study investigates the challenges and benefits perceived by teachers related to the uptake of SAD in their daily practice. The SADs were undertaking in science, technology and mathematics in primary and secondary schools in Denmark and Finland. The data used in this study include teacher-generated preparation and reflections forms, interviews with teachers,and an open-ended questionnaire.Our findings suggest that SAD holds prospects for fulfilling the purposes for both formative and summative assessment, with the highest prospects related to formative assessment purposes and characteristics. However, it needs time, change of classroom culture, and adjustments and careful implementation and routine building. In addition, teachers must be proficient in addressing the different aspects and levels of competences throughout the SAD.