Over the past 50 years, Japan has witnessed a dramatic decline in fertility and marriage rates, along with a rise in educational attainment, particularly among women. Married women now dedicate significantly less time on housework and more time on leisure and childcare. We develop a model that allows for various forms of technological change and relative prices surrounding families, and quantify their roles to account for the trends of family formation and time allocation. We find that neutral productivity growth leads to an increase in leisure time and a decrease in work hours. Technological changes that favor female labor supply and rises in the time and financial costs of childcare are the main factors contributing to the decline in fertility and marriage rates. Skill-biased technological change contributes to the rise in education levels, while advancements of home production technology explain the shift in married women’s time allocation from housework to the market work.