Petra Mathers was born in 1945 in Todtmoos, Germany and immigrated to the United States as a young woman. She has illustrated books for a number of well-known children's authors as well as those she has written herself.. The four-time winner of the annual New York Times prize for Best Illustrated Children's Book won the Ezra Jack Keats Medal for her first book Maria Theresa.

Before moving to the US, Mathers worked in a bookstore in Germany. Her first American career was a painter although she also worked as a waitress to "make ends meet."

Kisses for Rosa is based on a difficult time period during Mather's own childhood. Set in Germany shortly following the end of World War II, the story revolves around what happens to Rosa when her mother is hospitalized for tuberculosis and she is sent to live with relatives in the country. Rosa, who misses her mother very much, writes her every Sunday and concludes each letter with a unique kiss. When her mother gets well, Rosa also finds it difficult to leave the country, her relatives, and new friends. Actual family photographs from Mathers' childhood grace the end papers of the book.

Mathers has reported that she loves chickens, and her "Lottie's World" series, feature Lottie, a chicken, and her best friend, Herbie, a duck. The first volume is Lottie's Beach Towel which has been followed by Lottie's New Friend and A Cake for Herbie and Herbie's Secret Santa..

1985-- Ezra Jack Keats Award for Maria Theresa

1986-- New York Times Best Illustrated Children's Book of the Year for Molly's New Washing Machine (by Laura Geringer).

1988-- New York Times Best Illustrated Children's Book of the Year for Theodor and Mr. Balbini.

1990-- New York Times Best Illustrated Children's Book of the Year for I'm Flying (by Alan Wade).

1991-- Boston Globe and Horn Book magazine for Sophie and Lou.

1995-- Society of Illustrators Silver Medal for Kisses from Rosa.

1999-- New York Times Best Illustrated Children's Book of the Year for Lottie's New Friend.

1999-- Boston Globe-Horn Book Honor Book for Illustration for Lottie's New Friend.

1999-- Society of Illustrators Silver Medal for Lottie's New Friend.