Academic Resources Academic Advising Career Services Community Engagement Center for Teaching, Learning, and Research Course Scheduling Office Health Professions Honor Code Institutional Animal Care and Use Committee Institutional Review Board Must I Apply? Application Consent Form Deadlines Approved! Now What? Composition of the IRB FAQs Guiding Principles Useful Web Links Middlebury's IRB Policy Human subjects payment policy Learning Resources MiddCORE Phi Beta Kappa Registrar's Office Sciences Technical Support Services Student Fellowships & Scholarships Student Funding Database Undergraduate Research Visual Resources Collection Site Editor Log On Home » Academics » Academic Resources » Institutional Review Board » Middlebury's IRB Policy » Definitions » [Definition: Principal investigator] Principal investigator] principal investigator (PI): the primary person conducting the research. The principal investigator can be a professional or a student.