Each research laboratory at PHRI is headed by a Principal Investigator (PI), who determines the work to be performed in that lab in accordance with his or her own intellectual curiosity and the availability of funding. Research at PHRI is primarily hypothesis-driven. A description of ongoing research in each lab is included in each investigator's individual web page.

Each PI is responsible for obtaining his or her own grant funding. Most grants, including all grants provided by the National Institutes of Health (NIH), are based on competitive applications, which are reviewed and graded by peer review panels.

A major responsibility of each investigator is to communicate the results of their work with colleagues through public lectures and publications. Publication history in peer-reviewed journals is an important determinant of success in future grant applications and is a factor in faculty promotions.