Costa Rican law states that a foreigner can only be hired for a position if there are no Costa Ricans candidates available.
If a company wants to hire you they have to show proof of the effort taken to recruit a Costa Rican.
With a high level of education available in Costa Rica, a literacy rate of 95.8% and an increasing number of bilingual Costa Ricans, it is hard for a foreigner to find a job and obtain a work permit unless you are a specialist in a certain field. That being said, there are certain fields in which you are more likely to find a job. These fields are English or other foreign language teachers, tourism (temporarily) and environmental work. Working without a work permit also takes place, mainly in the tourism sector. Bear in mind that it is illegal to work without a permit.