In the past fifty years, scholars of human development have been moving from studying change in humans within sharply defined periods, to seeing many more of these phenomenon as more profitably studied over time and in relation to other processes. The Handbook of Life-Span Development, Volume 1: Cognition, Biology, and Methods presents the study of human development conducted by the best scholars in the 21st century. Social workers, counselors and public health workers will receive coverage of of the biological and cognitive aspects of human change across the lifespan.