The QUAL-PRAXIS Leonardo project uses the term practice- oriented assessment to refer to the assessment of work- based learning, to performance- and competence-based assessment employed as one of the possible methods of assessing VET students. The aim of practice-oriented (authentic) assessment is to evaluate knowledge and skills in natural situations. Assessment can be considered from different theoretical viewpoints. It is possible to observe differences between traditional and new thinking on assessment that are based on different conceptions of learning and teaching. One essential factor that distinguishes traditional thinking on assessment from new views is how the assessment context is understood. A further distinguishing feature between traditional and new views involves the question of who are seen as the assessors. In the traditional view on assessment student assessment is a task exclusively for the teacher. Constructivist thinking, by contrast, emphasises fostering the student's metacognitive thinking, self-directedness, learning-to-learn process, interaction, and willingness to collaborate. The Finnish experiment with skills demonstrations is being conducted on the basis of a constructivist conception of learning. Self-assessment undertaken as a part of the assessment of skills demonstrations is important also for a student's growth into a professional.