The longitudinal dataset is part of the OpenTeQ project, a cluster RCT conducted on 198 Italian middle schools to evaluate the impact of a light-touch training intervention on teachers relational skills. A two-wave longitudinal survey was conducted via CATI in 2016 and 2017, involving all the Italian language and math teachers operating in the 7th grade classes of the enrolled schools. In both occasions, they were asked to self-assess their efficacy in teaching using the Ohio State Teacher Efficacy Scale (OSTES). The two waves have been finally merged into a unique longitudinal dataset of 1,912 participants (response rate of 92%). These data are used to investigate the longitudinal invariance of the OSTES, evaluating whether different testing procedures led to similar conclusions about model fit and invariance of measurement and structural parameters. To ensure the complete reproducibility of findings, the Mplus 7 syntaxes for all model specifications are made available with the data.

1,912 individuals. All secondary schools of first grade located in the 11 selected provinces (Milano, Roma, Napoli, Como, Pavia, Novara, Verona, Bologna, Pesaro-Urbino, Ancona and Bari) and which had at least four first classes (grade 6) available to be directly involved in the training during the 2015/2016 school year were invited to participate in the experimentation. The complete list of schools with these characteristics was provided to the Research Group by the Italian Ministry of Education, for a total of 619 institutions. At the end of the contact and enrollment phases of the schools, 198 institutions decided to formally join. All Italian and mathematics teachers working in the second classes of these schools (Grade 7) were involved in the two waves of the survey

Computer-Assisted Telephone Interviewing (CATI)