Motivated by the Education Sustainable Development Goal of all young people achieving at least basic literacy and numeracy skills, the Organisation of Economic Co-operation Development has undertaken a pilot study of the Programme for the International Student Assessment (PISA) in developing countries. In one facet of this study, PISA is administered in six developing countries to 14-to-16 year olds who are either out-of-school, or in-school below grade 7. The target population is about one-to-three percent of the overall population for each of the participating countries. As members of the international team conducting the study, we presented the participating countries with several options to achieve adequate representation of the population. To simplify operations, reduce cost, reduce bias, and achieve sample size goals, a probability-based link-tracing approach was designed and attempted in countries as one of several approaches administered. We provide an evaluation of this approach and comparisons with alternatives, and describe its application toward providing proficiency estimates with adequate representation of the population.