Sweden is operating an usual scheme to ensure a steady supply of skilled concrete construction workers by training both youth and adults in all the theoretical and practical aspects of concrete technology. For youths there are two types of training: (1) an apprenticeship of 150 weeks, which includes 342 hours of theoretical education; (2) attendance at a vocational school plus an apprenticeship. A training group consists of a maximum of 16 pupils led by a professional teacher. Trainees spend their first 3 to 5 months in school workshops, and at the same time complete the major part of their theoretical studies. After this period the group, together with their teacher, is transferred to a local construction site. This on the job training continues for two years, during which the course of theoretical study is also completed. At the end of the job contract, the group is dispersed and the youths are set out as apprentices to approved contractors. Adult education also proceeds in groups of a maximum of 16 men. On-site training is again negotiated on a group contract basis. Groups are established for three categories of workers.