Executive SummaryThe formulation of an optimal marketing mix is quite complex when that mix must be effective across multiple international markets. At the crux of the problem is whether markets are similar to each other or interdependent and how this influences marketing mix decisions. Examining the marketing mixes of more than 30 automobile companies competing in the five major markets in Western Europe, it was found that easily changed marketing mix elements, such as prices and advertising, reflect market similarity, interdependence, and product-market conditions, although not always in the expected ways. The least flexible element, the number of models offered, does not appear to reflect any of these types of conditions. © 2000 John Wiley & Sons, Inc. eveloping an effective marketing strategy requires the manager to consider a variety of factors to insure that the strategy is successful. In addition to an assessment of the firm's capabilities, the manager must also evaluate changes in overall business conditions, competition, regulation, and consumer behavior. While this is sufficiently complex when planning marketing strategy in a single country environment, it is considerably more complicated planning marketing strategy in a multi-country environment. The manager not only has to assess each market individually, but also evaluate the various markets as they relate to each other.