This study is an item analysis of the Matching Familiar Figures Test-20. We examined error scores in the Matching Familiar Figures Test-20 to determine the influence of the difficulty of the test on the assessment of reflection-impulsivity. The sample included 700 participants aged between 6 and 12 years. The results obtained from the corrected item-total correlation showed moderate but significant values for the discrimination index in all age groups, although the lowest values were found in the 6-year-old group. The item difficulty data show that the test is quite difficult for 6-year-old participants and quite easy for 12-year-old participants, and more likely to show individual differences between these ages. The results suggest that the difficulty of the MFFT20 is appropriate for children between 6 and 12 years. However, because of some floor and ceiling effects, the results of this test for ages 6 and 12 should be interpreted very cautiously, especially for the 6-year-old group. (Contains 1 figure and 2 tables.)