This technical report provides detailed information on the rationale for using a common computer spreadsheet program (Microsoft Excel ® ) to calculate various forms of interobserver agreement for both continuous and discontinuous data sets. In addition, we provide a brief tutorial on how to use an Excel spreadsheet to automatically compute traditional total count, partial agreement-withinintervals, exact agreement, trial-by-trial, interval-by-interval, scored-interval, unscored-interval, total duration, and mean duration-per-interval interobserver agreement algorithms. We conclude with a discussion of how practitioners may integrate this tool into their clinical work. Keywords: computer software, interobserver agreement, Microsoft Excel, technology ABSTRACT T