“…During the past few decades, the conceptualization of psychotherapy as a nonlinear, dynamic, and complex process has been outlined in many publications and by different research groups (Schiepek et al, 1992a, 2014a,b; Orsucci, 2006, 2015; Hayes et al, 2007; Guastello et al, 2009; Pincus, 2009, 2015, 2016; Haken and Schiepek, 2010; Salvatore and Tschacher, 2012; Gelo and Salvatore, 2016). The interest in this approach is increasing, since it is capable of explaining important features of human change processes, including: discontinuous progress (sudden gains or sudden losses, Lutz et al, 2013; Stiles et al, 2003), missing proportionality and nonlinear relations between interventions and outcome (Muran et al, 1995; Hayes et al, 2007; Haken and Schiepek, 2010), unpredictability of long-term courses (Strunk et al, 2015), the dependency of human functioning on specific contexts and situative requirements (Kashdan and Rottenberg, 2010), the eigendynamics and individuality of evolutionary patterns (Barkham et al, 1993; Tschacher et al, 2000; Molenaar, 2004; Fisher, 2015; Fisher and Boswell, 2016), and the important role of client's contributions (e.g., motivation, ressources) to psychotherapeutic gains (Orlinsky et al, 2004; Bohart and Tallman, 2010).…”