ObjectivesExamine the effect of No Jab No Play policies, which linked vaccine status to childcare service entry without allowing for personal belief exemptions, on immunisation coverage. Study designImmunisation coverage rates from the Australian Immunisation Register were linked to regional level covariates from the Australian Bureau of Statistics between January 2016 and December 2019. Differential timings of policy rollouts across states were used to assess changes in coverage with the implementation of policies with generalised linear models. Quantile regression and subgroup analysis were also conducted to explore the variation in policy responses. ResultsBaseline mean vaccination rates in 2016 were 93.4% for one-year-olds, 91.2% for two-year-olds and 93.2% for five-year-olds. Increases in coverage post-policy were significant but small, at around 1% across age groups, with larger increases in two and five-year-olds. Accounting for aggregate time trends and regional characteristics, implementation of the policies was associated with improved full immunisation coverage rates for age one (post-year 1: 0.15% [95 %CI–0.23; 0.52]; post-year 2: 0.56% [95 %CI 0.05; 1.07]), age two (post-year 1: 0.49 [95 %CI: 0.00; 0.97]; post-year 2: 1.15% [95 %CI: 0.53; 1.77], and age five (post-year 1: 0.38% [95 %CI 0.08; 0.67]; post-year 2: 0.71% [95 %CI 0.25; 1.16]. The policy effect was dispersed and insignificant at the lowest quantiles of the distribution of immunisation coverage, and smaller and insignificant in the highest socioeconomic areas. ConclusionFindings suggest that No Jab No Play policies had a small positive impact on immunisation coverage. This policy effect varied according to prior distribution of coverage and socio-economic status. Childcare access equity and unresponsiveness in high socioeconomic areas remain concerns.