This article deals with the knowledge of the Karelian language of school children living in a Karelian village. Karelian is an endangered language and it is said that it is a language of old people, that is why I was interested in children’s knowledge of Karelian. The aim is consider how the children self-estimate their ability to speak, understand, read or write Karelian. This study shows that Karelian children do somehow know their heritage language. But to become skilful Karelian speakers children need plenty of help and support from their parents, teachers and from the community