Secondary data, often collected for billing purposes or administrative decision-making, may also be useful in the development of a program of research. In order to utilize secondary data, it must be managed, understood, and made ready for analysis. The purpose of this case study is to demonstrate secondary data cleaning and preparation for a multi-site and multi-year dataset using a step-by-step process. The use of secondary data is common in health services research because it often provides ample information to explore relationships and examine trends. Secondary data can be particularly useful when researchers have a limited amount of time and resources to conduct large-scale projects. Secondary data are often messy; therefore, using secondary data can be challenging. The analyst may not have access to detailed information about how the data were collected and coded, and there may be missing data, outliers, or extraneous data elements. The method used for this project was a modified version of a step-by-step guide to use and manage secondary data in research. The objectives of this guide are to encourage novice researchers to consider using secondary data and to provide a practical format to follow when doing so. The use of secondary data requires careful and thoughtful data management. Following a guide such as this aids in the organization of the project and ensures the many steps in the process are not missed so that data are well prepared for analysis.