This study explores the effect of multidimensional concept mapping instruction on students' learning performance in a web-based computer course. The subjects consisted of 103 fourth graders from an elementary school in central Taiwan. They were divided into three groups: multidimensional concept map (MCM) instruction group, Novak concept map (NCM) instruction group, and traditional textbook (TT) instruction group. Four weeks of experimental instructions were given to the three groups, respectively. Students' progresses were examined by pre-test and post-test measurements. The experimental results suggested that subjects in the MCM group performed significantly better than those in the NCM group which in turn performed significantly better than those in the TT group. Pedagogical implications were addressed, and conclusion and some suggestions were given. (Contains 6 tables and 8 figures.)