Co-teaching--or the use of more than one teacher in a classroom--has been commonly recommended as a means to promote inclusive education. The aim of the present study was to survey the actual frequency of co-teaching among different teacher categories in the comprehensive school level in one Finnish city. The data were collected through a questionnaire answered by two representative samples of teachers including 117 resource room teachers in the first survey, and 317 teachers of various teacher categories in the second. The results showed that co-teaching was a widespread phenomenon among resource room teachers and special class teachers but less frequent among other teacher groups. Overall, it was used only infrequently, typically from two to three hours a week. On a weekly basis it was implemented by every second special education teacher, every third classroom teacher and every sixth subject teacher. A comparison with a study from the early 1980s confirmed that the relative popularity of co-teaching had increased only slightly during the years. Although co-teaching is used sparsely, the teachers reported almost uniquely positive experiences obtained from it. It is argued that the promotion of co-teaching needs additional incentives if it is hoped to make it more common. (Contains 3 tables.)