Abstract Background In 2022, cocaine was the leading problem drug for which individuals sought treatment in Ireland, overtaking opioids for the first time. Despite increasing concerns about cocaine, there is limited longitudinal research examining factors associated with cocaine use in the general youth population. We describe levels of use and associated factors at 17 and 20 years old Methods Past-year cocaine use was studied at age 17 (N = 5965) and 20 (N = 4679) in a nationally representative cohort. Individual, family, social and environmental exposure variables were selected a priori. Weighted logistic regression models were fitted using Generalised Estimating Equations to multiply imputed and complete case data. Results Cocaine use was reported by 220 (4%) at age 17, and 1072 (23%) at age 20. Both individual and community factors predict use. Earlier alcohol initiation and having friends who use cannabis were strongly associated with increased odds of cocaine use at both ages. Those with parents who reported that neighbourhood intoxication or drug-taking was common had elevated odds of cocaine use at age 17. Conclusions Past-year cocaine use at 20 years old in this cohort is substantially higher than other international cohort studies. Levels of cocaine use increase significantly between 17 and 20 years old. Acknowledgement: Growing Up in Ireland (GUI) is funded by the Department of Children, Equality, Disability, Integration and Youth (DCEDIY). It is managed by DCEDIY in association with the Central Statistics Office (CSO). Results in this report are based on analyses of data from Research Microdata Files provided by the CSO. Neither the CSO nor DCEDIY take any responsibility for the views expressed or the outputs generated from these analyses. Key messages • Our study underscores significant cocaine use rates and correlations with early substance initiation and neighbourhood factors. • This emphasizes the necessity of a comprehensive, multilevel strategy for preventing cocaine use.