To some extent, quantity and quality can be traded off with one another (Becker and Lewis 1973), but declines in fertility can be so large that increased quality cannot compensate. We draw capacities in the widest sense of the term and include a broad array of features that make human beings more economically effective, such as emotional maturity and self-confidence, as well as standard human capital measures, such as education and skills. As such, human capacities are a broader category than human capital, but like human capital they are defi ned in terms of how they serve economic growth.