This paper empirically establishes the role played by the ecosystem related parameters in the emergence and growth of high technology start-up clusters in India. It is mainly based on secondary data from six major start-up hubs in India during the period 2005-2013. Our results throw up several interesting findings. First of all, we find that traditional infrastructure related factors or robust macroeconomic situation in general are not the most important drivers. What really seem to matter are the specific start-up ecosystem related factors - such as the Internet penetration, volume of deal flow, availability of VC funding and a pre-existing critical mass of relevant high technology businesses and skill-sets. Above all, our study points out that high economic growth alone will not automatically lead to spillovers in the form of a vibrant start-up ecosystem. Rather it has to be a product of conscious and concerted policy efforts at all levels that directly address the main challenges faced by the early-stage start-ups.