A programme of home-based intervention with two groups of pre-school severely subnormal children and their parents has produced apparently contradictory results; frequently visited children after initial superiority over infrequently visited children, later showed a deceleration in intellectual growth. Less frequently visited children conversely showed a rise in performance after an initial decrement. The interpretation is advanced that parents in the latter group were less dependent on the visiting therapist, and more able to take positive action to assist their children, and improve their own situation.