Capital now extends beyond financial equity to a constellation of tangible and intangible resources. Alongside book and market equity, social, human, relational, reputational, circular, and narrative forms of capital—often captured through ESG and aligned with the SDGs—shape enterprise value yet elude traditional accounting. Network capital connects firms to ecosystems, increasingly orchestrated by digital platforms. Sustainability is the unifying criterion: stakeholders, not just shareholders, must nurture it, with economics as its backbone. This chapter demonstrates how complementary capital sources co-create durable wealth, redefining the cost of capital, planning, and valuation, while reallocating resources to maximize long-term socio-economic returns.