Under-18 Marriage Prevalence in Nigeria" is a comprehensive research document sourced from the Multi-Indicator Cluster Survey (MICS 2021). This critical report sheds light on the pressing issue of under-18 marriages in Nigeria, providing in-depth insights into the prevalence, causes, and consequences of this harmful practice. In Nigeria, child marriage remains a complex challenge, with significant social, cultural, and gender dimensions. This document delves into the prevalence of under-18 marriages, which are characterized by girls being married off before reaching the age of 18. This practice is a blatant violation of child rights and often results from a web of factors, including gender inequality, cultural traditions, and economic pressures.