We thank Ron Martin for his insightful review essay on our book. Ron Martin has, as always, raised many of the issues that are central to understanding the development pathways of regions and to structuring research to generate robust insights that could be useful in sustaining or creating prosperous, inclusive regions. It is therefore a pleasure to be able to engage with his discussion in a way that hopefully will help us all to move forward collectively First, we agree with Ron Martin that research on regional development should be securely anchored in both theory and data. We respectfully disagree with his remark that our book is light on detailed data analysis. One of our major intentions in this book was to test a wide variety of explanations of regional growth and decline by marrying rigorous theory to as much data as possible, whether the issue be one of hard regional economics or "softer" institutional factors. To this end, the book is built upon what we believe to be an exhaustive, and at times innovative body of data-driven scholarship about our two metropolitan areas. Our study of each region's economic base and labor market is based on dis-aggregations of published data that are more detailed than in any other published study of two cities. This dis-aggregation method allow original empirical insights into specialization, labor demand, labor supply, skills, wages and task structures. For some of our labor and housing market analyses, we used detailed micro-data. Further, to our knowledge, there exists no comparable analysis of the structure of two big cities' civic and economic networks. The comprehensive and unique work in the book on innovation networks, entrepreneurialism, social capital, public spending are all rely heavily on original data analysis. We also undertake a detailed, historical content analysis of discourses and narratives about economic development in each region-a first for the literature. And finally, our extensive historical, qualitative and interview data, complement this wealth of quantitative material. In short, in the urban and regional economic development literature, we know of no equivalent integration of this wealth of original evidence on two cities. Second, Ron Martin raises the centrally important issue of the role of specialization in economic development today. In the cases at hand, we show that specialization leads to high regional incomes, in the past and in the present. Ron Martin seems to suggest that regional economic diversification might be a key to high income. The debate about specialization versus diversification suffers from both conceptual confusion and weak empirics. Kemeny and Storper (2014) report on some original econometrics that suggest that specialization and economic