China is entering a new demographic era of sustained population decline and rapid ageing. Drawing on various Chinese/international datasets and academic research, this Element documents the pace and uneven geography of the transition, evaluates its economic and social consequences, and proposes policy and institutional responses. It shows that fertility has fallen to among the world's lowest levels while life expectancy has risen, increasing the elderly share and shrinking the working-age population, especially in rural and interior regions. It examines pressures on pensions, healthcare, and long-term care as family support weakens, along with risks to labor supply, productivity, and economic dynamism. It then presents China-focused but transferable solutions, including home-equity release, retirement-age reform with job redesign and re-skilling, expanded long-term care insurance and services, and community models such as time banking and co-housing. It advocates pro-natalist policies that reduce educational competition, promote gender equality in childcare, and improve work–family compatibility.