Data to guide programmatic decisions in public health are needed, but frequently epidemiologists are limited to routine case report data for notifiable conditions such as sexually transmitted diseases (STDs) and human immunodeficiency virus (HIV). However, case report data are frequently incomplete or provide limited information on comorbidity or risk factors. Supplemental data often exist but are not easily accessible, due to a variety of real and perceived obstacles. Data matching, defined as the linkage of records across two or more data sources, can be a useful method to obtain better or additional data, using existing resources. This article reviews the practical considerations for matching STD and HIV surveillance data with other data sources, including examples of how STD and HIV programs have used data matching.