Access to guns in the home is associated with an increased risk of homicide, suicide, and unintentional shooting deaths in children and adolescents. Recent studies indicate that safe storage of guns is an effective method to decrease the risk of suicide and unintentional shooting deaths in children and adolescents. However, prior programs to promote safe storage of guns have been unsuccessful. This study tested the effectiveness of an intervention consisting of counseling, information, and provision of a gun lock. At follow-up, families in the intervention group were 4 times as likely to improve their storage of guns compared with the control group. However, the intervention did not significantly influence the removal of guns from the home. This study supports recommendations to discuss gun safety with families.