The Swiss TREE study (Transitions from Education to Employment) is an interdisciplinary multi-cohort survey tracking two large representative samples of compulsory school leavers. Based on the Swiss PISA 2000 sample, the first TREE cohort (TREE1) has been followed up throughout 10 survey waves over 20 years, with the last wave at average age 35 just now coming to its conclusion. The second TREE cohort (TREE2) is based on the sample of a national math skills assessment carried out among 9th graders in 2016 and has been followed up at yearly intervals since then. The presentation will (1) give some insights in the study and survey design and some of the major methodological challenges associated with it, (2) sketch the large scopeof research potential that TREE data provides, and (2) present some selected findings.