Imagine a former French major getting vocabulary tips from her young children That was the experience of Kristin Espinasse, an American who fell in love with a Frenchman and moved to his country to marry him and start a family. When her children began speaking the language, she found herself falling in love with it all over again. To relate the stories of her sometimes bumpy, often comic, and always poignant assimilation, she created a blog called "French Word a Day," drawing more admirers than she ever could have imagined.

With an approach that is as charming as it is practical,...