This volume contains the joint proceedings of the Workshop on Games for the Synthesis of Complex Systems (CASSTING'16) and of the 3rd International Workshop on Synthesis of Complex Parameters (SynCoP'16). The workshops were held in Eindhoven, The Netherlands, as satellite events of the 19th European Joint Conferences on Theory and Practice of Software (ETAPS'16). Both workshops are closely related in their topics as well as target audience and they shared a joint invited talk given by Giorgio Delzanno.