This review focusses on the transition of low-achieving school leavers - that is, those who left regular schools or special schools for students with learning disabilities without or with only a lower secondary school degree - into the vocational education and training (VET) system. Most of them do not enter regular VET programs after finishing school but participate in prevocational measures. Some of them are able to eventually enter regular VET programs while others are never able to do so. The review summarizes what we know about how participation in prevocational measures influences the probability of subsequently entering regular VET programs and if so, why. The review shows the little knowledge we have about for whom these measures generate new opportunities, and for whom they reinforce disadvantages. The review includes research on access to regular VET programs because selection processes at this stage result in a selective - not random - group of participants in prevocational measures and research on prevocational programs.