Background: This paper examines socioeconomic inequalities in mental health at school entry and explores changes in these inequalities over the first 3 years of school. Methods: The study utilises routinely collected mental health data from education records and demographic data at ages 4 and 7 years, along with administrative school-level data. The study was set in preschool establishments and schools in Glasgow City, Scotland. Data were available on 4011 children (59.4%)at age 4 years, and 3166 of these children were followed at age 7 years (46.9% of the population). The main outcome measure was the teacher-rated Goodman’s Strengths and Difficulties Questionnaire (4–16 version) at age 7 years, which measures social, emotional and behav...