One of the roles that interactive music systems can play is to operate as real-time improvisatory agents in an ensemble. A key issue for such systems is how to generate improvised material that is musically appropriate, and complementary to the rest of the ensemble. This chapter describes some improvisation strategies employed by the Jambot (a recently developed interactive music system) that combine both imitative and 'intelligent' actions: (i) mode switching based on confidence of understanding, (ii) filtering and elaboration of imitative actions, and (iii) measured deviation from imitative action according to a salient parametrisation of the action space. In order to produce appropriate rhythms the intelligent improvisation seeks to produce complementary rhythms by manipulating the level of ambiguity present in the improvisation to maintain a balance between novelty and coherence.