The document summarizes the methodology used in a PRISM assessment of the routine health information system in Guanajuato, Mexico. It provides background on Guanajuato's demographics and health facilities. A sample size of 157 health facilities was selected using a statistical formula to allow for inter-district comparison. The PRISM tools were adapted to Spanish and Mexican health terms. Field teams underwent training and piloted the tools. Data was entered using DEAT and EpiData software and analyzed in SPSS. Participants were asked to discuss in groups their experiences using the PRISM tools and how useful they were for assessing the RHIS.