If you are arriving by plane, we would recommend the following airports (the order reflects our preferences):
Hannover (approx. 110 km from Bielefeld)
Intercity trains from Hannover to Bielefeld leave at least every hour. The journey takes approx. 50 mins (it is not necessary to change trains). You can take the S-Bahn (No. 5, departs every 30 mins - duration 12 mins) or the airport tansfer bus from Hannover airport to the City Air Terminal at the train station (departures every 20/30 minutes, travel time approx. 25 mins) - or you can take a taxi.
Düsseldorf (approx. 190 km from Bielefeld)
From Düsseldorf airport there are direct connections to Bielefeld. The Intercity trains (ICE) leave every half hour during day time (duration approx. 1 ¾ hours). On some connections you may have to change at Dortmund, with the connecting trains stopping at the same platform.
Frankfurt/Main (approx. 320 km from Bielefeld)
There are Intercity trains from Frankfurt/Main airport to Bielefeld (departure at least every hour with a change in Cologne or Hannover - journey time approx. 3 hours). There is also the possibility of changing planes at Frankfurt/Main and flying from there to Düsseldorf or Hannover. This is generally more expensive and does not necessarily save time.
Amsterdam (Netherlands) (approx. 320 km from Bielefeld)
It might be cheaper and more convenient to fly to Amsterdam. There are two main lines: via Duisburg or via Osnabrück. The journey takes approx. 4 hours. Via Duisburg you have to change trains once; via Osnabrück you have to change twice (there are no Intercity connections on the Osnabrück line).
Paderborn/Lippstadt (approx. 80 km from Bielefeld)
There might be the possibility to book a connection flight from Frankfurt/M. or Amsterdam to Paderborn. Please note that the public transportation system from Paderborn to Bielefeld is not very convenient. Please ask the conference office for advice before booking.