This book constitutes the best paper selection from the First Workshop, WoCCES 2013, held in Brasília, Brazil, in May 2013, the Second Workshop, WoCCES 2014, held in Florianópolis, Brazil, in May 2014, the Third Workshop, WoCCES 2015, held in Vitória, Brazil, in May 2015, and the 4th Workshop, WoCCES 2016, held in Salvador, Brazil, in June 2016. The 7 revised full papers were carefully reviewed and selected from 41 submissions. The papers focus on important innovations and recent advances in the specification, design, construction and use of communication in critical embedded systems.