The aim of the study was to investigate the effects of support on knowledge acquisition of gifted learners and their flow and mood during inquiry learning. Sixty-four gifted primary school children were randomly assigned to one of three conditions differing in support given in an inquiry task. Results showed that learners who were allowed to experiment themselves learned more, experienced more flow, and felt more positive toward the task than those who were not given this opportunity, but only when they were guided through the inquiry cycle by prompts to generate hypotheses, perform experiments, and draw conclusions. The overall conclusion is that gifted children benefit more from open, complex tasks when their learning process is externally regulated.