Have you ever heard the story that your family's name was changed at Ellis Island? The United States' most famous port of immigration is also, unfortunately, the source of one of the many popular myths of genealogy - one that is still perpetuated with regularity in the media(just search Google News for keywords such as name changed "ellis island" and you'll typically find several recent articles which mention this topic). In actuality, inspection agents and Ellis Island rarely changed immigrants' names. That's not to say that mistakes weren't made, or that names weren't misspelled, but there is no known documented case of a name change occurring at Ellis Island, according to Marion Smith, senior historian for the immigration service.
The truth is, to be admitted to the United States, immigrants had to provide documentation from their country of origin. This information was used to compile passenger lists at the point abroad where the immigrant purchased his ticket. Once the immigrant arrived in the U.S., Ellis Island clerks were given these previously compiled passenger manifests, and checked off the names against the arriving immigrants. There was no need for them to write down names based on what the immigrant told them. Many Ellis Island immigration officials were themselves foreign-born, and were assigned to inspect immigrant groups based on the languages with which they were familiar. Ellis Island also employed dozens of full-time interpreters to help translate for immigrants speaking in more obscure tongues.
That's not to say, of course, that your ancestors never changed their names. They just probably didn't do it at Ellis Island. Many immigrants personally chose to change their names at some point - often to "fit in" - something done by my Toman ancestors soon after their arrival from Poland (even though I'm still not sure why Thomas is all that much easier of a name than Toman). But if your family name was changed at some point, it can probably be attributed to something other than a lazy or callous immigration official. Trace your family back to the immigrant ancestor and see for yourself!