Building on our 2017 article focussing on school library staff perceptions of teachers' information literacy, this article reports on the information literacy (IL) understandings and skills of teachers in post-primary schools (the age range for pupils in post-primary schools is 11-18) throughout Northern Ireland. Results of a comprehensive online teacher survey (n=426) indicated that, despite misplaced confidence in their own skills, teachers' IL understandings and skills were underdeveloped. The majority of respondents had neither received IL training nor included IL instruction in their teaching. The significance of these findings for theory, practice and policy relating to the teaching of IL skills, which are intended to equip young people to become active citizens and members of a skilled workforce, is discussed.