The National Institutes of Health (NIH) is inviting applications for the "Exploratory Clinical Neuroscience Research on Substance Use Disorders" funding opportunity, designated as NOFO PAR-23-157. This initiative aims to support exploratory clinical research focused on understanding the neurobiological mechanisms underlying substance use disorders (SUD), utilizing a phased R61/R33 award structure over a five-year period. The program is particularly relevant in addressing the ongoing public health challenges related to substance use, including the opioid crisis, and seeks innovative projects that explore neural circuitry and behavioral processes associated with SUD. Eligible applicants can include a wide range of institutions, including educational, governmental, nonprofit, and for-profit organizations, with funding potentially reaching $500,000 for the R61 phase and an unrestricted budget for the R33 phase, contingent upon meeting specific milestones. Interested parties should contact NIH Grants Information at grantsinfo@nih.gov and note that the application deadline is June 21, 2023, with subsequent review cycles planned.