Validation of early childhood diet recalls by surrogate responders decades later has not been possible because of a lack of diet records from the distant past. Between 1948 and 1970, parents of children participating in the Fels Longitudinal Study (Kettering, Ohio) completed a 7-day diet record for their children every year from birth to age 18 years. In 2005-2006, all surviving women (n = 59) with a child aged 3-5 years when diet records had been collected were asked to complete a 42-item food frequency questionnaire (FFQ) pertaining to 1 of their children's diets at age 3-5 years. One or more diet records were available for 48 children. The authors calculated Spearman correlation coefficients for correlations between food, food-group, and nutrient intakes from the diet records and the FFQ and deattenuated them to account for the effects of within-person variation in the diet records on the association. For foods, the median deattenuated correlation coefficient was 0.19 (range, -0.31 to 0.85); moderate-to-high correlations were found for some specific foods. Correlations for food groups were slightly higher (median, 0.27; range, -0.14 to 0.85). Correlations for nutrient intakes were consistently low (median, 0.06; range, -0.35 to 0.27). Overall, the FFQ did not validly reflect overall preschool diet when completed by mothers 4 decades later.