I completely adore the Betsy-Tacy series of books by Lovelace, which follows Betsy and her friends from age six to adulthood and marriage. Written for her daughter, the books follow Betsy in age--little chapter books to begin with, then over to the young adult section for the grown Betsy books: high school and college. I completely remember jumping from children's to young adult to read the next one in the series. Beautifully illustrated by Lois Lenski, then Vera Neville, the entire series is consistently wonderful (except for the last book wherein independent Betsy gets married and turns a little neurotic). I especially love
Betsy and the Great World, where Betsy takes a year to travel and heads home as WWI breaks out. So romantic!
