Over 1.6 million children and young people in England have an identified special educational need (SEN), representing 18.4% -- more than one in every six -- of all pupils currently in school. This report describes the lives of young people born in 1999/2000, who would have taken their GCSEs in the academic year 2014/15, and uses the SEN Code of Practice 2002 classifications of School Action, School Action Plus, Statement (mainstream) and Statement (special school) to capture the level of need and related provision received. With a focus on understanding the diverse nature of the subgroups within the SEN population, this report explores the characteristics, post-16 experiences and early adult outcomes (age 19/20) of young people who received different levels of SEN provision during school and compares them with their peers without any identified needs. Many of the results presented in this report replicate other research in describing the characteristics of children and young people associated with having SEN, such as being a boy, coming from more socioeconomically disadvantaged homes, and having lower levels of academic achievement. The findings also build on the extant literature and explore early adult outcomes across a range of areas reflecting a greater focus on preparation for adulthood in a broader sense, providing insight into the variation across these groups into areas of mental health and wellbeing, health-related behaviours and indicators of independent living, as well as extending understanding of variation in post-16 attainment and labour market outcomes.