Background: This study assessed parent reactions to school-based body mass index (BMI) screening. Methods: After a K-8 BMI screening program, parents were sent a letter detailing their child's BMI results. Approximately 50 parents were randomly selected for interview from each of 4 child weight-classification groups (overweight, at risk of overweight, normal weight, underweight) to assess parent recall of the letter, reactions to BMI screening, and actions taken in response to the child's BMI results. Results: Most parents found the BMI screening letter easy to read and had poor recall of numerical information (eg, the child's BMI percentile) but good recall of the child's weight classification (e.g., normal weight or overweight). Most parents, and ethnic-minority parents in particular, supported school-based BMI screening. Parents of children whose weight was outside of the normal range were more likely to recall receiving the letter and talking to the child and the child's doctor about it. Parents who recalled their child as being overweight were more likely to report changing the child's diet and activity level. Most parents, and ethnic-minority parents in particular, wanted their child to participate in an after-school exercise program. An overweight condition in parents, but not children, was associated with an interest in family-based cooking and exercise classes. Conclusions: Most parents, and ethnic-minority parents in particular, viewed school-based BMI screening and after-school exercise programs favorably. Parents reported taking action in response to a BMI result outside of the normal range. Parents who were overweight themselves were particularly interested in family cooking and exercise classes. (Contains 4 tables.)