While a strategic imperative for financial institutions, major differences currently exist among banks' abilities to convert their customers to using the Internet. In addition, not a lot is known as to what drives those differences, although one can easily hypothesize that on-line banking adoption must be due to a combination of demand (“pull”) and firm (“push”) factors. This paper presents a statistical appraisal of the determinants of on-line customer penetration for a cross-sectional sample of the major incumbent banks in Western Europe for the combination of the years 1988 to 2000. “Pull” factors play a large role in explaining customer conversion to Internet banking, yet bank-specific factors (or “push” factors) are not marginal. Among others, banks with traditionally high cost-effectiveness and that already offer wide private ATM coverage for their customers are also the ones which have already started to migrate a larger proportion of their customer base on-line. Interestingly, among all “push” factors analyzed, cost-effectiveness emerges as the largest leverage effect on customer conversion. Finally, a cluster analysis supplements the regression results along the axes of “pull” and “push”, and identifies a set of early movers and laggards among the banks in our sample. Generally speaking, those first-movers already exhibit stronger off-line profitability than laggards, which may indicate that the on-line marketplace may reproduce performance off-line (i.e., currently successful banks have nothing to fear from aggressive start-ups).