Peter,

According to the Census Bureau "if either parent is foreign born, children are second generation." Interesting. So if one parent can trace lineage to the Mayflower but the other parent is foreign born, the children are second generation.

As far as assimilation, from my experience most second generation Americans think of themselves as assimilated. Almost all immigrants want to assimilate, although many have difficulties. Their children do not. It would take a special effort to prevent assimilation of one's native born children, especially with today's mass culture.

William Wang: Technically (according to the Census Bureau) your father and you are both "first generation," as strange as that seems (father and son of the same generation). Perhaps, you are "1.5 generation." Obviously there is much ambiguity here and some of the distinctions presented here get blown apart by such situations. For example, for my entire childhood my father was a "resident alien" (the official term at the time for a Green Card holder). Later when I was an adult he became a naturalized citizen. So I was first generation until my father was naturalized at which time I became second generation. Interesting. According to the my interpretation of the Census Bureau definition, I was always second generation. My father was not an American (so "no generation") until he was naturalized at which time he became first generation, so during my childhood there was no first generation.