The extensive (>1000 states, ca. 8m people), long-lived (ca. 800-200 BCE), and intensively studied ecology of culturally Greek city-states offers a unique opportunity to analyze the effects of institutional innovation and the dissemination of institutions (as well as other aspects of culture) over time and space. Greek city-states were highly competitive, with one another and with their non-Greek neighbors. And yet the Greek city-state ecology was also characterized by extensive exchange of goods and services, based on local specialization, exploitation of comparative advantage, and deep investments in human capital. Certain democratic institutional innovations, proved to be highly adaptive under these conditions. Those innovations were quickly adopted (and adapted to local conditions) by many, but not all Greek states, allowing us to formulate and test hypotheses about the relationship between public institutions and economic and cultural development.