Professional and client domains that have published cases, theory, or research using process concepts of Delta Theory include the following: families managing child disability (Gallimore et al., 1999); literacy development (Goldenberg, Gallimore, & Reese, 2005); psychotherapy (Miltenburg & Singer, 1999; Tharp, 1999); counseling (Portes, 1999); community development (Roberts, 2005; O’Donnell & Tharp, 1990, 1982; O’Donnell et al., 2001, 1993); organizational development (Engeström & Middleton, 1996); delinquency and juvenile justice (O’Donnell, 2003); mentoring (Gallimore, John-Steiner, & Tharp, 1992); self-directed behavior change (Watson & Tharp, 2006); and enhancing parent-school leadership (Bolívar & Chrispeels, 2011.)

Education has been the enterprise most extensively explored using Delta Theory concepts. The research evidence is favorable for their effectiveness in advancing academic engagement and achievement (for reviews of that research, see Tharp & Dalton, 2007; Tharp et. al, 2004, 2000; Tharp & Gallimore, 1988). When a delta condition is stabilized – even at the classroom level or lower – a continuing pattern of successful influence and change flows continuously through curricular and value goals as they advance. However, in transnational schools of the common tradition, the delta phase psychosocial system is the rare exception, principally because of insufficient responsive influence, there being a paucity of joint activity in schools’ academics; therefore, there are few opportunities for the development of delta-phased psychosocial systems. Instead, schools are typically organized by an uninterrupted reliance on existent affinities. At least in this respect, transnational schools are much more alike than different.Although schools for youth have the widest and deepest institutional mandate for influence and change, their typical operational condition – as opposed to their formal responsibilities – is, if at all, only marginally delta; it is best characterized as beta – a condition maintaining relative stability of social class and social organizational functioning. Of course, this is not by intention, but rather through institutionalized habits and ignorance of contemporary developmental theory. I have described this fully elsewhere (Tharp & Dalton, 2007; Tharp et al., 2000): In transnational schools of the common tradition, activity settings allowing a rich quantity and quality of responsive influence; assistance and regulation are appallingly rare; and the same psychosocial systems, as established by neighborhood, culture, and network, continue uninterrupted for years.