Four theoretical frameworks were used to explore causations of turnover amongst high school teachers in Nigeria: (1) teachers' personal health, (2) work-family life, (3) job satisfaction, and (4) actual turnover intention. Quantitative data were obtained from 925 public high school teachers in Ogun State, South-Western Nigeria. Cronbach's Alpha reliability procedure, regression modelling and t-test were used to analyse a total of 96 causations of turnover. Ad hoc analysis returned an Alpha value of 0.78. However, this improved to 0.93 when the causation factors were reduced to 64 -- those with highest item-rest and item total correlations. The findings showed that job (dis)satisfaction, personal health and work-family life conflict are prominent amongst the issues that trigger the intention of Nigerian high school teachers to quit their jobs voluntarily. Insights from the findings will help funding administrators in prioritising strategic decisions around mitigating turnover.