Carel Jansen is co-author of four Dutch textbooks on professional communication: 
Leren Communiceren
– Professioneel Communicereren – Formulierenwijzer  – Handleidingenwijzer

Together with his colleagues Leon de Stadler and Aline Douma, Carel Jansen edited Communicate as a Professional, a communication textbook in English, based on Leren communiceren. 

Carel Jansen is a member of the editorial board of Information Design Journal and the Journal of Technical Writing and Communication.

From 2019 until 2020 Carel Jansen was the chair of the Dutch language society Onze Taal; he also chaired the Vrienden van Onze Taal.

Carel Jansen was one of the initiators of a national research program on text comprehensibility. For more information (in Dutch) see this page at the website of the Dutch Research Council NWO.

Since 2017, Carel Jansen has chaired the steering group of a Dutch plain language campaign called Direct Duidelijk. For his contribution to a debate in April 2021 about the use of ‘B1′ as a standard for writing in plain Dutch, click here and here.

Since November 2019, Carel Jansen has chaired the board of the Buurthuiskamer Aduard, the community centre in the village where he lives.

Since March 2023, he has chaired the board of Dorpsbelangen Aduard, the organisation that represents the village of Aduard in communication with the overarching municipality Westerkwartier.

Carel Jansen participated in the European health literacy research project IROHLA  (December 2012 until December 2015), resulting, among other things, in the Health Literacy Centre Europe portal, in the further development of which he is now involved.

Together with colleagues from South-Africa and the Netherlands, Carel Jansen was involved in EPIDASA and HACALARA, two research projects on HIV/AIDS Communication. 

Since 2019, Carel Jansen has chaired the Project group Uitdrukkingsvaardigheid (Language and Communication Competence), consisting of experts in the field of language and communication education in Dutch universities. He then became a member of a working group formed by the Taalunie (Union for the Dutch Language) to advise the Dutch Minister of Education on ways to advance the language proficiency of Dutch students in higher education. The basis for the resulting advice was an extensive literature review of which Carel Jansen was one of the authors.

In 2022, on account of his expertise in the field of language and communication, Carel Jansen was appointed to an advisory group to support the Vakvernieuwingscommissie Nederlands, a committee set up by the Ministry of Education to revise the examination programs for the school subject Dutch.

Carel Jansen actively promotes and supports the so-called Boektrommel Projek (the Book Box Project) in South Africa.