Summary.The two‐fold purpose of this study was to validate the School Failure Tolerance (SFT) scale and to identify developmental patterns and sex differences in children's academic risk‐taking and tolerance for failure. Fourth‐, fifth‐, and sixth‐graders were given the SFT and a chance to select and work 12 of 80 or 90 problems, of varying difficulty, in each of three content areas: mathematics, spelling and vocabulary. The SFT reliably predicted the difficulty level chosen by students at all grade levels and in all content areas. Students at all grade levels chose problems considerably below their ability levels as defined by mean performance on standardised achievement tests. This low risk‐taking tendency increased markedly with grade level. Students chose problems resulting in mean absolute success of between 77 per cent and 92 per cent — levels far in excess of the 50 per cent level theoretically associated with optimum motivation. Furthermore, mean scores on two of three SFT subscales decreased significantly from grade four to grade six. There were no sex by grade interactions and only one of ten variables revealed a significant sex difference. These findings are interpreted and discussed in terms of motivational theories and clas