OPA is involved in research collaborations with other Federal agencies. OPA is one of the major funding contributors to the National Survey of Family Growth (NSFG), a long-time national survey on reproductive health topics conducted by the National Center for Health Statistics. NSFG has completed six cycles and currently proceeds on a continuous interviewing basis. Additionally, OPA has funded a number of research initiatives at the National Institute of Child Health and Human Development, most notably providing support for the National Longitudinal Study of Adolescent Health , which is undertaking a fourth wave of longitudinal data collecting.