The purpose of the NIDA Animal Genetics Program is to identify genetic, genomic, and molecular (epi)genetic variants that underlie: 1. Phenotypes associated with addictive behaviors and/or vulnerability to distinct stages along the substance use disorder (SUD) trajectory (e.g. initial/acute use, escalation of use, acquisition of tolerance, dependence, uncontrolled use, abstinence and relapse or recovery); 2. Behaviors associated with SUD (e.g. impulsivity, novelty seeking, delayed discounting, and other genetically-associated phenotypes); and 3. Comorbidities that demonstrate genetic correlations with phenotypes and behaviors linked with SUD (e.g. anxiety, stress, poor maternal care, social defeat, and other paradigms). Applications may examine any type of variant, including single nucleotide variants (SNVs), indels, large and small structural variants, and all types of mobile DNA. NIDA encourages applications that take genomics, multi-omics, and/or data-based approaches that integrate multi-level omics data, delineate gene networks, and/or uncover the function of known or newly discovered genetic or epigenetic variants. NIDA expects these studies to uncover novel mechanisms that contribute to SUD and facilitate the discovery of targets for intervention and guide the development of individualized therapeutics to treat these different aspects of SUD.