The purpose of this study was to explore whether the results of Tree Based Regression (TBR) analyses, informed by a validated cognitive model, would enhance the interpretation of item difficulties in terms of the cognitive processes involved in answering the reading items included in two forms of the Michigan English Language Assessment Battery (MELAB). A cognitive model was first generated to explain the performance of the MELAB reading items, and then validated by expert judgment and student verbal protocols. Next, the validated model was used in the TBR analyses to obtain the final trees for each form. Finally, the cognitive processes (i.e., reading processes and testing strategies) measured by each item were traced back for each item in the terminal nodes of each tree. The results revealed that TBR, informed by a supportable cognitive theory, appears to be a promising addition to statistical item analysis that can be effectively used to enhance the interpretation of item analyses results. (Contains 3 tables, 7 notes, and 3 figures.)