Tijdschrift voor Economische en Sociale Geografie – 2006, Vol. 97, No. 1, pp. 59–68. © 2006 by the Royal Dutch Geographical Society KNAG Published by Blackwell Publishing Ltd., 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden MA 02148, USA GOING UNDERGROUND: IMMIGRATION POLICY CHANGES AND SHIFTS IN MODES OF PROVISION OF UNDOCUMENTED IMMIGRANTS IN THE NETHERLANDS JOANNE VAN DER LEUN* & ROBERT KLOOSTERMAN** *Department of Criminal Sciences, Leiden University, PO Box 9520 NL-2300 RA Leiden, the Netherlands. E-mail: j.p.vanderleun@law.leidenuniv.nl **AMIDSt and Department of Geography, Planning and International Development Studies, University of Amsterdam, Nw. Prinsengracht 130, 1018 VZ Amsterdam, the Netherlands. E-mail: r.c.kloosterman@uva.nl Received: November 2004; revised August 2005 ABSTRACT The turn of the century in Europe is marked by social changes that have affected immigration policies. In the Netherlands, internal controls have been tightened in order to curb illegal residence and employment. On the basis of interviews with undocumented workers before and after significant policy changes, shifts in labour market position are observed. Matching strategies have become less transparent and labour conditions have deteriorated. In combination with demographic changes, i.e. the arrival of new groups of undocumented immigrants, the gap between illegal immigrants and the receiving society has widened and labour has gone further underground, resulting in unintended outcomes of the restrictive policy. Key words: Illegal immigration, undocumented, migration policy, regulation, informal economy INTRODUCTION Horticulture is, even in this post-industrial age, still a very important money-maker for the Dutch economy. The growing of flowers and vegetables in large, nearly contiguous areas of hot-houses in the coastal area – where the yearly average hours of sunshine is the highest in the country – can arguably be considered as an advanced spatial cluster of economic activities. Its strong competitiveness is based primarily on the input of highly skilled labour and the development of a complex set of dedicated institutions that enable innovation, knowledge spill-over and a continuous supply of high- quality seedlings. This kind of setting is, of course, very much like other innovative clusters. There is, however, one other special feature that strongly contributes to make Dutch horti- culture so competitive, which is the widespread use of illegal labour. Without undocumented workers toiling away in the hot-houses, there would be a much less competitive and, hence, a much smaller horticultural sector in the Netherlands. The presence of undocumented workers is a well-known fact and, moreover, has moved far beyond being a temporary adjustment to new conditions. Just as Schlosser (2003) has observed for California, illegal labour has become a structural component of this sector. As in the United States, illegal labour in the Netherlands is not confined to horticulture. Significant numbers of undocumented workers can be found in other sectors as well; notably in restaurants and catering, cleaning, child-care, domestic labour and construction. For quite some time, as in the United States, undocumented workers were more or less