This is a cross-sectional study conducted with 258 teachers from nine state schools in two municipalities of São Paulo state with the purpose of assessing their work ability. A questionnaire with socio-demographic and health/work conditions data and the Work Ability Index (WAI) was performed. Most teachers were females, 41.9 yr old on average (SD 9.4), and with an undergraduate degree (95.7%). The work ability was considered good for 42.6% and moderate/low for 35.3%. In linear regressions models, which used the two domain model, the significant variables for a decrease in WAI were: individual perception of a worsening in the health situation (p<0001), having children (p=0.0003 / p=0.0001), difficulty in sleeping well at night (p=0.0009 / p=0.0014), history of physical pain in the previous six months (p<0.0001 / p<0.0001), being a teacher with a contract (p=0.0007) and working as a teacher for a longer time. (p=0.0183). Public investments on the work conditions of teachers are important to recover and to maintain their work ability.