Both Venice and Miami are high-density coastal cities that are extremely vulnerable to rising sea levels and climate change. Aside from their sea-level location, they are both characterized by large populations, valuable infrastructure and real estate, and economic dependence on tourism, as well as the availability of advanced scientific data and technological expertize. Yet their responses have been quite different. We examine the biophysical environments of the two cities, as well as their socio-economic features, administrative arrangements vulnerabilities, and responses to sea level rise and flooding. Our study uses a qualitative approach to illustrate how adaptation policies have emerged in these two coastal cities. Based on this information, we critically compare the different adaptive responses of Venice and Miami and suggest what each city may learn from the other, as well as offer lessons for other vulnerable coastal cities. In the two cases presented here it would seem that adaptation to SLR has not yet led to a reformulation of the problem or a structural transformation of the relevant institutions. Decision-makers must address the complex issue of rising seas with a combination of scientific knowledge, socio-economic expertize, and good governance. In this regard, the "hi-tech" approach of Venice has generated problems of its own (as did the flood control projects in South Florida over half a century ago), while the increasing public mobilization in Miami appears more promising. The importance of continued long-term adaptation measures is essential in both cities.