Title {1}	Effectiveness of the Elos 2.0 prevention programme for the reduction of problem behaviours and promotion of social skills in schoolchildren: study protocol for a cluster-randomized controlled trial
Trial registration {2a and 2b}.	RBR-86c6jp (http://www.ensaiosclinicos.gov.br/rg/RBR-86c6jp/). Registered 11 February 2019.
Protocol version {3}	February 11, 2019 Original version
Funding {4}	This study received a Research and Innovation Grant for the Prevention of Mental Disorders and Use of Alcohol and other Drugs (“Pesquisas e Inovações em Prevenção de Transtornos Mentais e Uso de Álcool e Outras Drogas”) funded by the Brazilian Ministry of Health (TED #176/2017). The funder’s roles consist of selecting the most suitable grant applications and implementing the Elos 2.0 Programme
Author details {5a}	1Department of Psychiatry, Universidade Federal de São Paulo, São Paulo, Brazil; 2School of Public Health, The University of Hong Kong, Hong Kong SAR, China, 3Department of Clinical Psychology, University of São Paulo, São Paulo, Brazil; 4Department of Preventive Medicine, Universidade Federal de São Paulo, São Paulo, Brazil
Name and contact information for the trial sponsor {5b}	Brazilian Ministry of Health Address: Esplanada dos Ministérios, Bloco G, Edifício Sede, Brasília - DF, Brazil, 70058-900 https://www.gov.br/saude/pt-br +55 (61) 3315-3580/2005
Role of sponsor {5c}	The funding agency is not involved in the design of this study and will have a role during its implementation, but not in the analyses, interpretation of the data and decision to submit results. The sponsor declares that it has no commercial interest or sources in the application of this trial.