This case study of Ecuador analyzes intergenerational changes and their impact on development, revealing major demographic, economic, and spatial transformations. Using data from the 2011–2012 Urban–Rural Household Income and Expenditure Surveys, National Transfer Accounts (NTA), and CELADE population projections for 1950–2100, the analysis, guided by the life-cycle model, shows how demographic and economic dynamics interact across different stages of life. Findings confirm a clear demographic transition from a predominantly young society to one with an increasing share of older adults. This shift, driven by declining birth rates, longer life expectancy, and improved health care, has reshaped population distribution and economic behavior. The first demographic dividend has emerged as the working-age population expanded, boosting national income, while early signs of a second dividend, linked to higher savings and capital accumulation among older cohorts, suggest rising productivity potential. Intergenerational inequalities in income, education, health, and social protection are becoming more visible, influencing patterns of housing demand, construction, and urban expansion. Aging and social polarization may intensify pressures on infrastructure, land use, and public services if not addressed through integrated planning. Overall, the results highlight the importance of policies that leverage the remaining demographic window while promoting sustainable urban development and preparing for the fiscal, social, and spatial challenges of an aging population.