Coastal dunes protect large parts of the Netherlands against flooding. The formation of new dunes in front of the existing foredunes may strengthen flood defences in the face of rising sea levels. This thesis explores the ecological and geomorphological drivers of new dune development along the natural and nourished Dutch sandy coast and ends with exploring the potential of mega-nourishments for dune development. This thesis shows that I) beach morphology determines the potential for new (embryo) dune development, beaches of 300 m and wider being most favourable. II) Rate of development of embryo dunes is enhanced by sand supply and summer precipitation and depressed by winter storm erosion, III) vegetation composition modifies the sensitivity of the dunes to erosion, IV) Embryo dunes can facilitate development of species-rich green beach vegetation by creating shelter against over sanding on accreting coasts but compete for space on eroding coasts.