Deviation from dominant religious, philosophical or political norms was a common phenomenon in 16th and 17th century Europe. Toleration of heterodox beliefs was not the rule in most European contexts. This led the heterodox to develop strategies of dissimulation in order to avoid undesirable consequences. This essay focuses on the phenomenon of dissimulation by using concrete examples. Particular emphasis is given on the cases of Jews in Venice and Thessaloniki who reverted to dissimulation in order to avoid their persecution by political and religious authorities.