This study evaluates the citizenship behaviour of customers and employees from a private school and aims to identify if variables like teachers' self-efficacy and job satisfaction precede such a behaviour. The study was developed in the teaching field, where parents are considered as customers, teachers are employees from private schools that teach 6 to 18 years old students. The method consists of personal surveys applied to teachers and parents in order to measure their perceptions and opinions. The quantitative analysis applied was structural equation modelling. Results confirmed a positive and significative relationship between teachers' self-efficacy, job satisfaction, organisational citizenship behaviour (OCB) and promoter citizenship behaviour. The study revealed that it is more probable that if a school has teachers showing a good level of self-efficacy, intrinsic job satisfaction and OCB, customers will be more satisfied and would recommend their private school to friends and relatives.