The Participant Use File (PUF) is pulled from the National Cancer Data Base (NCDB), a joint program of the American College of Surgeons Commission on Cancer (CoC) and the American Cancer Society (ACS), and is offered as an added value to clinical investigators at CoC-Accredited cancer programs who desire to conduct their own studies. The aim of the CoC and NCDB is to position investigators to successfully use the PUFs. There are a number of resources available to investigators. Chief among these is an on-line and publicly accessible PUF Data Dictionary (http://ncdbpuf.facs.org/), which has been developed as a resource to investigators using the NCDB PUF data files. Before proceeding with analyses, all investigators are encouraged to familiarize themselves with the on-line PUF Data Dictionary. This dictionary provides a wealth of information designed to facilitate the analytic use of the data items in the PUFs. This document is designed to expedite investigators’ familiarization with the PUF data, and provides a list of the registry data items that should be considered when defining the analytic cohort of patients for proposed analyses. This introduction does not serve as a replacement for the on-line PUF Data Dictionary, which should be consulted before data analysis begins. Additionally, the NCDB provides a reference list of recent abstracts and publications that have been developed from PUF files, and categorized by cancer site.