We are requesting access to the age data on these variables at age 17-19 in order to undertake initial descriptive analyses of the all of the behaviours separately, followed by more complex analyses exploring the extent to which and ways in which these behaviours cluster using multiple regression, adjustment for missing data using multiple imputation techniques, and use of various latent variable techniques. The work is being undertaken as part of the DECIPHer programme of work on multiple risk behaviours in adolescence. The work is directed by a multi disciplinary group of researchers, led by Prof Rona Campbell and Prof Matt Hickman, with involvement from Dr Ruth Kipping, Dr Jon Heron and Dr Michele Smith. Dr Michele Smith will undertake the descriptive analysis and Dr Jon Heron will undertake the latent class analysis. Michele Smith is supported by Jon Heron and hence there is no need to incur the time (and therefore costs) of a data buddy to facilitate the use of the data. Following the initial analysis of behaviours at ages 17-19, we will submit a separate application to the ALSPAC Executive for outcomes such as education, morbidity and mortality