Generation	Key Influences	Birth Dates
Matures “The Greatest Generation”	Depression, New Deal, World War II, GI Bill	1909 - 1945
Boomers The nation’s largest generation	Great Society, Economic Prosperity, Suburban Expansion, Sexual Revolution, Rock ‘n Roll, Drugs	1946 – 1964 Early Boomers (1946 - 1955) Late Boomers (1956-1964)
Generation X	Divorce, Aids, Sesame Street, MTV, Crack, Game Boy, PC	1965 – 1976
Generation Y, Millenials Echo Boomers The nation’s second largest generation	The Internet, eCommerce, Boomer Parent Indulgence, 9-11, Oklahoma Bombing, Reality TV, Digital Music	1977-1994

Notes

1. Since there are no hard and fast rules defining birth dates for each generation, numerous researchers and writers have redefined the dates based on their beliefs and particular purposes. Thus, other sources may cite different birth dates for generational segments that are different from those cited here. For example, Baby Boomer birth dates have also been listed as 1945-1964, Generation X birth dats as 1965-1984, Generation Y as 1985-Present (2008).
2. Matures are sometimes broken into additional groups: "The GI Generation", 1905-1924, defined by its participation in WWII, and "The Silent Generation" 1925-1944.
3. Generational time spans vary because they are based on key influences during the formative years of that generation. Thus, the 1909-1945 birth dates of Matures span a 36 year period, while the 1946-1964 time span of Boomers is an 18 year period.

Sources:
MRI 2008
AdAge 060208
Rocking the Ages: The Yankelovich Report on Generational Marketing