This research aimed to examine (a) the perceived by teachers behavioral problems of kindergarten children, (b) the relationship between those problems, kindergarten children’s ability self-perception, in language and mathematics, and (c) the perceived by teachers kindergarten children’s school performance. The participants were 50 teachers and 194 kindergarten children, both genders, from various socioeconomic backgrounds. The teachers’ responses to the Behavior Checklist for Preschool Children revealed that behavioral problems do exist even in this early age and the most frequent ones’ were the psychosomatic problems. The kindergarten children’s responses to a questionnaire, which was adapted to their age, showed that the behavioral problems were positively correlated to the kindergarten children’s ability self-perception, in language and mathematics, as well as to the perceived by teachers kindergarten children’s school performance. The results, also, illustrated that kindergarten children’s ability self-perception was higher in mathematics, than in language, indicating the need to study not only the general school performance, but also the school performance in different cognitive subjects. The results are discussed in terms of their importance for their implications in the education and future research.