The implementation of panel studies in developing countries can prove valuable in driving evidenced-based policies. Case analysis from panel studies in developing countries are therefore useful in offering guidance and insight to deal with the immense challenges of implementing and following-up a panel study in a developing country. The aim of this paper is to describe the follow-up process within Birth to Twenty (Bt20), a birth cohort study in Johannesburg, South Africa, over the past 16 years; and to outline retention strategies and insight within the context of an urban, developing country setting. The main issues considered are: attrition (periodic and absolute), movement of individuals, name changes, cohort management and lessons learned.