A study designed to test the Piagetian theory that distinct stages in the organization of memory relating to horizontality correspond to successive stages in operative level was conducted with 154 twelve- to fourteen-year-old subjects. Loglinear and path analysis models were used to describe the association between operative level and spatial memory clinically assessed initially and again 6 months later. The analysis revealed a significant correlation between the two operative assessments and the two memory assessments. Subjects assessed as operative initially on an angle measure task had 2.6 times the odds of both correct initial and correct 6-month memories as those who were assessed as non-operative. Subjects assessed as operative initially on a bottles task had 8.7 times the odds of correct memory at 6-months as those who were not. Subjects assessed as operative initially on both tasks had 22 times the odds of correct memory at 6-months as those who were assessed as non-operative in both assessments. (Author/MP)