Studies have shown that males and females differ in their susceptibility to nicotine dependence (ND) and other cigarette smoking behaviors.  With regard to genetics, heritability of ND is estimated at 50%, and specific variants in the nicotinic acetylcholine receptor (nAChR) genes are known to increase risk of ND. These associations were discovered from genome-wide association studies (GWAS) of ND and other smoking behaviors, yet no prior studies have evaluated differences in genetic associations by sex. This study aims to: (1) conduct a genome-wide joint 2df meta-analysis of ND accounting for interaction with sex and (2) test SNPs with the most significant meta-analysis results, when accounting for interaction with sex, for independent replication.