His father, who came from the Rhine area, worked as a technician in the steelworks in Linz and died in a sick bay in 1943 after military action on the Eastern Front.

During his studies, he was an active member in Catholic organisations and held a mandate of the Austrian Students' Association.

From 1970 onwards, van Staa was managing director of the Institute for Rural Development, working especially in the field of social and regional research.

Josef Willi, he established the internationally renowned Research Department for Agricultural Ecology at the Institute.

In spring 1995, van Staa was elected vice president of the Austrian Towns Association.

In July 1996, van Staa was elected vice president of the Chamber of Local Authorities of the Congress of the Council of Europe.