The aim of the study was to investigate what kinds of assessment practices class teachers and special educational needs (SEN) teachers use in assessing first grade students' pre-reading skills (letter knowledge and phonological skills). Further, we investigated to what extent teachers were able to identify difficulties in pre-reading skills of the lowest achievers. The accuracy of teacher ratings of students' pre-reading skills was studied by comparing teacher ratings to actual test scores. The data from two Finnish longitudinal studies were used: JLD sample (class teachers, n = 91; SEN teachers, n = 51; 200 students) and First Steps sample (class teachers, n = 136; SEN teachers, n = 34; 598 students). Results showed first, that most class teachers used qualitative assessment and SEN teachers also relied on tests. Secondly, although teacher ratings correlated with the test scores, closer investigation of sensitivity and specificity of the teacher ratings revealed that a number of children in need of extra support for their early reading development according to test scores remained unidentified. Moreover, there were some students identified by the teacher to have difficulties despite test scores not confirming that. The findings underline the importance for developing more specific and reliable assessment tools for teachers to use for pedagogical purposes, and respectively, the need to pay more attention to early identification of reading difficulties in teacher training program curricula.