About half the world's population knows and uses two or more languages in everyday life, and an increasing number of parents are raising their children bilingual. This makes a resource on what it means to become and be bilingual all the more necessary. This book brings together a selection of posts from the author's highly successful Psychology Today blog, grouped by topic into 15 chapters. The topics covered include, among others, what it means to be bilingual, the extent of bilingualism, how someone becomes bilingual, how bilingualism is fostered in the family, the bilingual mind and brain, and bilingualism across the lifespan. It also includes the author's lively interviews with other experts, delving into their research and their own experience as bilinguals. Written in a highly engaging, readable style, this book is suitable for anyone who wants to better understand those who live with two or more languages.