This article aims to illustrate the central underpinning role that observation has had in the development of attachment theory and research, and in clinical work informed by attachment theory. Also, the paper aims to highlight reflective functioning in clinical practice and how it can be shown to ignite positive change processes, with illustrations provided from our ongoing trauma-informed clinical work with our Group Attachment Based Intervention or GABI in our work with vulnerable parents and their infants and toddlers. In pointing to how reflective functioning informs clinical practice in GABI, the paper aims to highlight what is proposed as fundamental to therapeutic action with infants, toddlers, children, adolescents, adults/parents and that is a strikingly new relationship with a benign, supportive other, who helps one practice novel ways of thinking, feeling and acting that may later become habitual across contexts.