Global agricultural is threatened by the presence of the root-knot nematode Meloidogyne incognita, which cause severe losses of crop yield by damaging the root systems of the plant. To control root-knot nematodes, crops can be made more resistant by the use of plant resistant genes. These plant resistant genes provide protection to the plant against root-knot nematodes. Unfortunately, the available resistance gene used against root-knot nematodes is temperature sensitive and therefore not functional at temperatures above 28oC. Additionally, there are nematode populations developing that are not affected by the resistance gene anymore. This led to the search for alternative strategies to develop durable nematode resistance crops. In this thesis Sonja Warmerdam describes an approach to identify so called susceptibility genes (S-genes) that can be used as an alternative to develop resistance against root-knot nematodes. S-genes are plant genes that are necessary for the nematode to successfully infect the plant. In this thesis several S-genes were identified in Arabidopsis that affect the level of infection by root-knot nematodes. This knowledge provides propsects to identify S-genes in crops for the development of durable resistance against root-knot nematodes.