Pharmacogenomics is the study of genetic factors that influence drug response. Pharmacogenomics combines pharmacology and genomics to identify genetic predictors of variability in drug response that can be used to maximize drug efficacy while minimizing drug toxicity in order to tailor drug therapy for patients, thus improving patient care and reducing healthcare costs. In this chapter we review the field of pharmacogenomics in its current state and clinical practice. Recent research, methods, and resources for pharmacogenomics are reviewed in detail. We discuss the advantages and challenges in pharmacogenomic studies. We elaborate on the barriers to clinical translation of pharmacogenetic discoveries and the efforts of various institutions and consortia to mitigate these barriers. We also discuss applications and clinical translation of pharmacogenomic research moving forward, along with social, ethical, and economic issues that require attention. We conclude by previewing the use of big data, multi-omics data, advanced computing technology, and statistical methods by scientists across disciplinary boundaries along with the efforts of government organizations, clinicians, and patients that could lead to successful and clinically translatable pharmacogenomic discoveries, ushering in an era of precision medicine.