The Wonder Weeks Team

Xaviera Plas
Xaviera PlasCEO
Being Dr. Frans’ en Dr. Hetty’s daughter, Xaviera knows The Wonder Weeks inside out. She is responsible for the worldwide rights and product development.

Anita Peereboom
Anita PeereboomMarketing Manager
As head of daily operations, Anita’s responsibility is to implement all developed marketing means at the right stage and in the right way in every country.
Angelotte Admiraal
Angelotte AdmiraalWeb Manager
The websites, social media, designs, … all these marketing means require constant new input. Angelotte makes sure that, parents around the globe get all the information they need.

Scientific Curriculum Vitae

Frans X. Plooij

Click edit button to change this text.Born in 1946, Frans X. Plooij studied in the Netherlands with Adriaan Kortlandt, University of Amsterdam, with Hein Oomen, University of Nijmegen, and with Gerard Baerends, University of Groningen, where he received his Ph.D. in 1980.
In 1971–73, he and his wife Hetty van de Rijt worked with Jane Goodall in the Gombe National Park, Tanzania, East-Africa, on infant development in free-living chimpanzees. In 1973-76 he worked with Robert Hinde in the Medical Research Council unit on the Development and Integration of Behaviour, University Sub-department of Animal Behaviour in Madingley, Cambridge, England; in 1976-80 at the department of Developmental Psychology, University of Nijmegen, the Netherlands; and from 1981 to 1993 as head of the department of Research and Development at the institute for Child Studies of the City of Amsterdam, the Netherlands, where, among other things, he participated in European Union SOCRATES-LINGUA projects concerning the implementation of an innovative second- and foreign-language teaching method for small schoolchildren.

From 1993 to 1998, he was a professor at the Department of Developmental and Experimental Clinical Psychology, University of Groningen.

He is currently president of the International Research-institute on Infant Studies (IRIS) at Arnhem, the Netherlands, initiator of the European project on “the intercultural study of infantile regression periods” (ISIRP), and director of Kiddy World Promotions B.V., a consulting firm that serves companies producing products related to children, such as toys.

Dr. Plooij was Vice-president for Information of the International Society for Human Ethology from 1989-1993, Vice-president of the Institut Européen pour le Development de tous les Enfants (IEDPE), served on the editorial board of the journal “Ethology and Sociobiology”, and was member of the panel of assessors of the Journal of Clinical Child Psychology and Psychiatry.

He is a full member of several international, scientific societies in the domains of child development and behavioural biology, and of the New York Academy of Sciences.

In addition to numerous scientific publications, Dr. Plooij has written several best-selling parenting books, one of which, The Wonder Weeks, has been published in many languages, from the USA to Japan. The Wonder Weeks became a Worldwide bestseller on infant development and has sold over 1.5 million copies!

Read Introduction by Frans Plooij

Scientific Curriculum Vitae

Hetty van de Rijt

Born in 1944, Hetty van de Rijt-Plooij studied Educational Psychology at the University of Nijmegen, the Netherlands and worked following graduation in an institute for the mentally handicapped. From 1971 to 1973, with her husband Frans X. Plooij, she studied infant development in free-living chimpanzees with Dr. Jane Goodall in the Gombe National Park, Tanzania, East Africa. From 1973 to 1976, she studied with Prof. Robert Hinde in the Medical Research Council unit on the Development and Integration of Behaviour. In 1976 her daughter Xaviera was born. She obtained her Ph.D. in Physical Anthropology at the University of Cambridge, England in 1982.
As a researcher at the University of Amsterdam, the Netherlands from 1986 to 1990, she studied the development of human babies in their home environment through direct observations, filming, and in-depth interviews with their parents.

As lead author with her husband as co-author, she wrote the best-selling parenting book The Wonder Weeks, which has been published in twelve languages, from the USA to Japan. She designed a parental support and education program called Leaping hurdles, based on the Wonder Weeks and published a scientific evaluation study to report on the results of this program. She died far too young at the age of 59.