A World Health Organization report (e.g., Richter, 2004) on importance of caregiver-child relationships as a context for growth and development of young children throughout world noted that: Sensitive and responsive caregiving is a requirement for healthy neurophysiological, physical and psychological development of a child. Sensitivity and responsiveness have been identified as key features of caregiving behavior related to later positive health and development outcomes in young children. (p. 1) One of developmental consequences of sensitive and responsive caregiving is secure infant/adult attachment (Bowlby, 1988). Secure attachment is generally understood to be an affectional bond between an infant and an adult caregiver (1) that has two elements: (1) infant seeking out attachment figure in times of distress and need and (2) infant having ability and confidence to engage in activities separate from attachment figure (Ainsworth, 1989). The development of attachment relationship is recognized as one of most important aspects of human social and emotional development (e.g., Lamb, Ketterlinus, & Fracasso, 1992). This is case, in part, because secure attachment has been found to be related to enhanced cognitive, social, and emotional development throughout childhood and early adolescence (Bukatko & Daehler, 2001; Fagot & Kavanagh, 1993; Hazen & Durrett, 1982; Matas, Arend, & Sroufe, 1978; Sroufe, Egeland, & Kreutzer, 1990). Many theories as well as variations of theories have been posited for explaining sources and consequences of secure infant attachment (see e.g., Cassidy & Shaver, 1999; Egeland & Erickson, 1993). John Bowlby (1969) is credited with original formulation of attachment theory, and Mary Ainsworth (Ainsworth & Wittig, 1969) is credited with highlighting importance of caregiver sensitivity as a determinant of secure attachment. Gewirtz and his colleagues proposed a behavioral, or operant learning analysis, perspective of secure infant attachment that considers caregiver sensitivity and responsiveness as having reinforcement properties and infants' responses to caregivers' behavior as having differential consequences on caregivers' reactions (e.g., Gewirtz, 1972a, 1991; Gewirtz & Boyd, 1977; Gewirtz & Pelaez-Nogueras, 1991). According to Gewirtz, attachment is parsimoniously explained by fact that child behavior is cued and reinforced by caregiver responses and may have either positive or negative effects on child behavior that in turn is directed toward caregiver (e.g., type of attachment). In Gewirtz's (1991) own words, the dyadic functional relations between cue and reinforcing stimuli from attachment figure/object person and child's responses they control that connote attachment of child to attachment figure may occur in any segment of life from infancy onward (p. 250). The purposes of this article are to summarize findings from: (a) two practice-based research syntheses of relationships between caregiver sensitivity and secure infant attachment (Kassow & Dunst, 2004, 2005) and (b) one practice-based research synthesis of interventions for strengthening caregiver sensitivity to child behavior (Dunst & Kassow, 2004). A practice-based research synthesis involves review and integration of research evidence where focus of investigation is same or similar environmental (intervention) characteristics and how variations in characteristics are related to variations in consequences of different events or experiences. These kinds of research syntheses differ from more traditional research reviews and syntheses by disentangling and unpacking what matters most in terms of explaining relationship(s) between different environmental experiences and their consequences (Dunst, 2007; Dunst, Trivette, & Cutspec, 2002). …