Wouters wrote his dissertation Informalization about the obvious changes of the western customs and manners in the 20th century.
[citation needed] His theory of informalisation implies that a long-term process of formalisation – of formalising manners and disciplining people – had been dominant from the sixteenth up to the last quarter of the nineteenth century, after which a process of informalisation has prevailed: behavioural and emotional alternatives increased, together with demands on emotion management or self-control.
Wouters proceeded to elaborate this theoretical perspective in a variety of studies of the late-nineteenth and twentieth-century social and psychic processes, focusing mainly on emotion regulation, dying and mourning, sexuality, and the emancipation of women and children.
His systematic and empirical approach has been an important contribution to this field of study[citation needed] and is highly appreciated throughout the ranks of his fellow workers and students.
[citation needed] Cas Wouters has written articles in English, Dutch, Spanish and German on changes in relationships between men and women, the dying and those who live on, and on related, more general social and psychic processes.