Neural cell adhesion molecules were discovered as important determinants in ontogenetic development,where they play crucial roles in proliferation,cell migration,neuritogenesis,myelination,neuronal survival and death,synaptogenesis and synaptic plasticity.Initially unexpected,yet particularly exciting are their functions in the adult nervous system when adhesion molecules recapitulate,at least to some extent,their developmental features in synaptic plasticity,that is learning and memory,as well as in regeneration after trauma when the nervous system is required to be "on the move".Also,function-beneficial adhesion molecules have been shown to counteract decline of nervous system functions in chronic neurodegenerative diseases.With the adhesion molecules L1 and NCAM carrying polysialic acid and the HNK1 glycan,examples will be given of regeneration pro-active molecules with therapeutic potential.