1. Introduction; Peter Rosa, Marita Rautiainen, Timo Pihkala, Maria José Parada and Allan Discua Cruz.- Part I. Theoretical and Methodological Reflections.- 2. Theoretical Insights into the Nature, Diversity and Persistence of Business Groups; Peter Rosa and Timo Pihkala.- 3. The Methodological Challenges of Researching Family-owned Business Groups; Peter Rosa, Marita Rautiainen and Timo Pihkala.- Part II. The Emergence of Family Business Groups through Portfolio Entrepreneurship.- 4. The Emergence of a Family Business Group: The Role of Portfolio Entrepreneurship; Marita Rautiainen and Timo Pihkala.- 5. Managing Portfolio Business: A Case Study; Donato Iacobucci and Peter Rosa.- 6. Entrepreneurial Growth through Portfolio Entrepreneurship: The Entrepreneurial Career Ladder; Peter Rosa.- 7. Resourcefulness and the Informal Economy: From Pluriactivity to Portfolio Entrepreneurship; Naveed Akhter and Ernestine Ning.- Part III. Complexity and the Development of Family Business Groups.- 8. The Dynamics and Complexity of Family Business Groups; Kajari Mukherjee, Marita Rautiainen, Timo Pihkala and Peter Rosa.- 9. Understanding the Dynamics of Business Group Development: A Transgenerational Perspective; Maria José Parada, Naveed Akhter, Rodrigo Basco, Allan Discua-Cruz, Sarah Fitz-Koch.- 10. Deciphering Ownership of Family Business Groups; Timo Pihkala, Sanjay Goel, Marita Rautiainen, Kajari Mukherjee and Markku Ikävalko.- 11. Governance in Family Business Groups: Resolving Multiple Contingencies to Sustain Entrepreneurial Capability; Sanjay Goel, Tuuli Ikäheimonen, and Marita Rautiainen.- Part IV. Family Business Groups in Different Local Contexts.- 12. The Contribution of Family Business Groups to the Local Innovation Environment; Suvi Konsti-Laakso, Jussi Heikkilä, Marita Rautiainen, Satu Rinkinen and Naveed Akhter.- 13. Resilience and Family Business Groups in Unstable Economies; Allan Discua Cruz, Rodrigo Basco, Maria José Parada, Antonio Malfense-Fierro, Cristina Alvarado.- 14. Entrepreneurship and Rural Family Identity: Understanding Portfolio Development in a Family Farm Business; Sarah Fitz-Koch, Sarah Cooper and Allan Discua Cruz.- Part V. Conclusion.- 15. Conclusions; Peter Rosa, Marita Rautiainen, Timo Pihkala, Maria José Parada and Allan Discua Cruz.