Learning, and particularly assessment practices, that encourages a self-determined approach enhances feelings of well-being and achievement motivation. Students (n = 137) in a common first-year unit were the participants for an evaluation of the impact of assessment. The Intrinsic Motivation Inventory and the Brunel Mood Scale were used to assess psychological reactions. A repeated measures comparison for each motivation and mood variable was conducted using mixed-model analysis. Changes in all moods were significant at week 7, when the greatest number of assessment items per student was due. For this particular week, negative moods also increased, along with a decrease in the positive mood of vigour. The intrinsic motivation variables of interest/enjoyment and perceived competence were significantly lower in week 7, with pressure/tension being significantly higher. For this group of students the demands of assessment have been shown to have a psychological impact. (Contains 3 figures and 1 table.)