Criminological theories and widespread assumptions about crime suggest that the modus operandi involved in sexual crimes should have changed over time given various contextual changes, such as better criminological knowledge (e.g., forensic awareness) as well as improved investigative techniques (e.g., forensic evidence analysis). The aim of this study was to test whether the modus operandi patterns of individuals having committed a sexual assault against female strangers have changed over time during the period of 2003–2017. More specifically, the study has identified changes in the trends of monthly counts and (relative) participations for sexual assaults during the study period in France. The measure of participations – a concept borrowed from the field of criminal career – was used to overcome the inherent limitations associated with this type of data. Results show that despite some significant changes in the modus operandi involved in sexual crimes, overall the modus operandi patterns appear to be fairly stable over time. The findings are discussed in light of their theoretical and practical implications.