This study describes the development of the SAPS and investigates its reliability and validity within the context of the Health Behaviour in School-Aged Children Survey (HBSC) which gathered data on representative samples of school pupils aged 11, 13 and 15 in Scotland and England. In the development of SAPS, following a comprehensive review of the literature, two small-scale empirical studies were carried out (one qualitative and one quantitative). Regarding the validation process, the reliability and validity of the SAPS was assessed in a sub-sample (n = 7159) of pupils who completed the HBSC survey and were identified as owning pets. Factor analysis resulted in a one-factor solution (explaining 67.78 % of the variance); Cronbach’s alpha for the scale was 0.894. The item-total correlation ranged from 0.368 to 0.784. A linear model showed that attachment to pets was associated with age (being 11 or 13 years old), being a girl, white ethnicity, and considering a pet as one’s own. SAPS scores were also positively associated with quality of life. The total variance in SAPS explained by these variables was 15.7 %. Effect sizes of associations were medium (age, considering a pet as one’s own) and small (ethnicity, age, gender, quality of life). The study concludes that SAPS is a coherent and psychometrically sound measure. It is associated with a range of demographic variables and quality of life, which confirms its utility as a new succinct measure of children’s and young people’s attachment to pets for use in health and social science research.