In the first five years of life children spend a large proportion of their time in the family home and increasingly in the non-parental child care (NPCC) environment. International research suggests that access to high quality NPCC may facilitate healthy child development (e.g. children’s early learning, intellectually, emotionally and socially), particularly for children from more disadvantaged backgrounds. There is limited Australian research describing the quality of NPCC on children’s developmental outcomes. There is also no universal definition of NPCC quality. Our research attempts to quantitatively define the quality of NPCC using a set of multidimensional indicators based on Australian child care standards and research evidence of key components of high quality care. A measure of NPCC quality was developed using two waves of data from the Longitudinal Study of Australian Children (infant cohort). The indicators of quality in our measure are divided into three domains 1) carer education, 2) activities, and 3) relationships. The aim of this paper is to present the methodological approach and challenges in quantitatively defining this measure of quality and present its predictive ability on children’s receptive vocabulary and social-emotional outcomes.