Chairman and confidential clerk Daily Administration study group Pedagogy (1988 - 1992);

Member education committee study group Pedagogy (1995 - 1998).

Chairman Algemene Beroeps Bekwaamheids Registratiecommissie van de Nederlandse Vereniging van Pedagogen en Onderwijskundigen (NVO). In this capacity I have organized and attended to courses for supervisors ABBR (1987 - 1996);

Member Beleidscommissie Beroepsbekwaamheidsregistraties (NVO) (1995 - 1998);

Member Remedial Education of the ‘Coördinerend Orgaan Nascholing en Opleiding’ (CONO) in de GGZ (1992 - 1997);

Chairman scientific group ‘Speciaal Rekenen’ of the Nederlandse Vereniging voor de Ontwikkeling van het Reken-Wiskunde Onderwijs (NVORWO) (1987 - 1998);

Member editorial staff journal School & Begeleiding (1985 - 1995);

Member editorial staff journal Willem Bartjens (1987 - 1994);

Member editorial staff journal School & Management (1992 - 1999);

Member of various ministerial advice committees concerning the renewing of the education of arithmetic and mathematics (1984 - present);

Member scientific staff handbook Hulp bij leerproblemen (1994 - now);

Member editorial staff journal Orthopedagogiek: Onderzoek en Praktijk (2001 - present);

Organizer Alumni days Learning Disabilities (1992 - 2018);

Organizer Inter academic scientific days Learning Disabilities Utrecht (1988, 1992 en 1998);

Member scientific committee project ‘Ouders en rekenen’ (1998 - 2018);

Member scientific recommendation group project ‘Realistisch rekenen voor zeer zwakke rekenaars’ (1999 - 2017);

Member scientific consultation group concerning calculate – math for Ministry of Education (1992 - 2019);

Member committee accompaniment project ‘Bolleboos; onderkenning van begaafdheid’ (1998 - 2002);

Chairman Education committee Pedagogy (1999 - 2001);

Chairman Exam committee Pedagogy (2000 - 2009);

Member of the steering committee ‘Inzicht’ Dutch Scientific Organization (NWO) (2000 - 2001);

Referent of the Teaching and Learning Programme Steering Committee and the Research Priorities Board of the Economic & Social Research Council (ESCR; United Kingdom) (2000 - 2014);

Chairman Education Institute Learning Disabilities (2001 - 2004);

Chairman Capacity group Pedagogy (2001 - 2004);

Member Scientific committee Stichting Integratie Gehandicapten (Belgium) (2002 - present);

Member Working party Kwaliteit en Effectiviteit Voor- en Vroegschoolse Educatie (2002);

Vice president Department of Pedagogical and Educational Sciences, Utrecht University (2001 - 2009);

Member Accreditation committee NVO Basis-Orthopedagoog (2002 - 2021);

Director master Special Needs Education Utrecht University (2001 - 2010);

PhD supervisor (Van de Rijt, 1996; Schopman, 1998; Kroesbergen, 2002; Aunio, 2006; Van der Molen, 2009; Toll, 2013; Friso-van den Bos, 2014; Prast, 2017; Stolte, 2021; Zwart, 2021; Kaskens, 2022).