Surveillance studies provide important information that allows for the identification of trends in pathogen incidence and antimicrobial resistance, including identification of emerging pathogens at national and global levels. Routine surveillance is critical for creating and refining approaches to controlling antimicrobial resistance and for guiding clinician decisions regarding appropriate treatment. The traditional approach has been to monitor pathogen antimicrobial susceptibility; numerous large studies have been performed, and their designs have evolved over time. Longitudinal studies are particularly useful because important information can be obtained by comparing data over time. Another approach to surveillance, that of monitoring antimicrobial use, can help to identify trends in dosing, to prevent the development of resistance. Several studies have incorporated this approach into their methods, and both large and small studies have attempted to correlate antimicrobial use data with antimicrobial resistance data. Overall, care must be taken to coordinate programs for optimal utilization of resources, to avoid duplication of effort.