This is not a comprehensive list; rather it is a jumping off point gathered by best of lists from Time Magazine and various libraries.
Anne of Green Gables by Montgomery, Lucy Maud (1908)
A Tree Grows in Brooklyn by Betty Smith (1943)
The Catcher in the Rye by J.D. Salinger (1951)
Lord of the Flies by Golding, William (1954)
A Separate Peace by Knowles, John (1958)
To Kill a Mockingbird by Harper Lee (1960)
The Outsiders by Hinton, S. E. (1967)
From the Mixed-Up Files of Mrs. Basil E. Frankweiler by E.L. Konigsburg (1967)
A Wizard of Earthsea by Ursula K. Le Guin (1968)
I'll Get There. It Better Be Worth the Trip by John Donovan (1969)
Are You There God? It's Me, Margaret. by Judy Blume (1970)
A Hero Ain’t Nothin’ but a Sandwich by Alice Childress (1973)
The Chocolate War by Cormier, Robert (1974)
Forever by Blume, Judy (1975)
Tuck Everlasting by Natalie Babbitt (1975)
Roll of Thunder, Hear My Cry by Mildred D. Taylor (1976)
The Westing Game by Ellen Raskin (1978)
A Swiftly Tilting Planet by Madeleine L'Engle (1978)
Homecoming by Cynthia Voigt (1981)
The House on Mango Street by Sandra Cisneros (1983)
Weetzie Bat by Block, Francesca Lia (1989)
How the Garcia Girls Lost Their Accents by Alvarez (1991)
The Giver by Lois Lowry (1994)
Ella Enchanted by Gail Carson Levine (1997)
If You Come Softly by Jacqueline Woodson (1998)
Holes by Louis Sachar (1998)
Speak by Anderson, Laurie Halse (1999)
Monster by Walter Dean Myers (1999)
Angus, Thongs and Full-Frontal Snogging by Rennison, Louise (1999)