We analyse worker self-selection, with a special focus on teachers, to explore whether worker composition is generally endogenous. We analyse laboratory experimental data to provide causal evidence on particular sorting patterns. Our field data analysis focuses specifically on selection patterns of teachers. We find that teachers are more risk averse than employees in other professions, indicating that relatively risk averse individuals sort into teaching occupations under the current system. Using survey measures on trust and reciprocity we find that teachers trust more and are less negatively reciprocal than other employees, and establish differences in personality based on the Big Five concept.