In this study, the influence of class size on students’ classroom discipline, engagement and communication school teachers from 16 purposely selected secondary schools out of a population of 4529 senior secondary teachers from Ekiti State, Nigeria was used for the study. The study adopted a descriptive survey research design. The instrument used for data collection was Influence of Class Size on Classroom Discipline, Engagement and Communication Questionnaire (ICSCDECQ) with the 21). Four research questions and three null hypotheses guided the study. The research questions were answered using Mean rating and Standard Deviation scores and the hypotheses were tested using Chi-square. The study revealed that class size has significant influence on senior secondary classroom discipline, engagement and communic influence on senior secondary classroom discipline, engagement and communic among others that, senior secondary schools in Ekiti State, Nigeria should adopt a maximum of 40:1 student teacher ratio (small class size) for effective classroom discipline, engagement and communication. ation. It was recommended among others that, senior secondary schools in Ekiti State, Nigeria should adopt a maximum of 40:1 student teacher ratio (small class size) for effective classroom discipline, engagement and communication. among others that, senior secondary schools in Ekiti State, Nigeria should adopt a maximum of 40:1 students-teacher ratio (small class size) for effective classroom discipline, engagement and communication.