This paper describes how clustering problems can be resolved by neural network (NN) approaches such as Hopfield nets, multi-layer perceptrons, and Kohonen's 'self-organizing maps' (SOMs). We emphasize the close relationship between the NN approach and classical clustering methods. In particular, we show how generalized SOMs are derived by stochastic approximation from a new continuous version (K-criterion) of a finite-sample clustering criterion proposed by Anouar et al. (1997). In this framework we determine the asymptotic behaviour of Kohonen's method, design a new finite-sample version of the SOM approach of the k-means type, and propose various generalizations along the lines of classical 'regression clustering', 'principal component clustering', and 'maximum-likelihood clustering'.