Schools have become increasingly aware of the prevalence, seriousness and negative impacts of bullying. Investigation into the direction and strength of the relationship between social health factors and bullying victimisation during early adolescence and the determination of a critical time to focus school-based bullying intervention programs is a high priority. Data were collected using a self-completion questionnaire four times over 3 years from 3459 students aged 11-14 years during the transition from primary to the end of the second year of secondary school. Results show the path coefficients for bullying victimisation to social heath factors were stronger at the beginning of secondary school than the reverse paths, with bullying victimisation associated with greater loneliness, less peer support, less connectedness to school and feeling less safe at school. Reciprocal relationships between bullying victimisation and social health were found during the first 2 years of secondary school. Consequently, the time prior to the transition to secondary school and within the first 2 years of secondary school appears to be a critical time to implement a whole-school bullying intervention program to reduce victimisation.