It should be noted, though, that barriers may exist to being involved in engaging activities. For instance, using the data from the National Longitudinal Study of Youth (Child Supplement), Hart and colleagues (Hart, Atkins, & Ford, 1998) discovered that a low socioeconomic status (SES) may act as a barrier to volunteering (which Hart and colleagues consider to be an indicator of moral development) because it could preclude low SES participants from having the opportunities to be involved in volunteer activities.