Is it that they follow the certain rules of omertá? Or that they were originally the basis on which the crime underworld was formed? Same question, really, but: how can Capone's crew not be considered as Mafian (is that a term?)? Did the frightened-of-needles kingpin actually declare he wasn't a Mafia Family?

Thanks in advance,
Mick

Interesting question, Mick. If you're referring to American Mafia families:
Prior to Prohibition, organized crime in America was small-time and local. Every city had a "red light district" where "vice" (prostitution, gambling, drugs, illicit booze since many communities were officially "dry" before Prohibition) flourished. In ethnic neighborhoods (especially Chinese, Irish, Jewish and Italian), crimes of extortion flourished. In Italian neighborhoods, the racketeers were most often Sicilian or Neapolitan, since that's where most Italian immigrants to the US came from. The Sicilians were always better organized because they were more clannish than the Neapolitians. But they were essentially small-time. They didn't really call themselves "Mafia" officially. Rather, they saw themselves as "men of honor," or "men of a tradition," as they thought of themselves in Sicily. Omerta was part of their tradition.
Jewish gangs (and to a lesser extent, Irish gangs) dominated the Prohibition rackets in nearly all American cities except Chicago. There, the Torrio-Capone "Outfit" was the biggest (but not the only) gang. Even though most members of the Capone gang were Italian, he never considered it a "Mafia family," and many non-Italians held high places in his mob. As I mentioned many times before: there was a Mafia in Chicago called the "Unione Siciliano" that was like a civic association with muscle. Capone respected the Unione, but the two never competed.
To get to the point (and I'm certain you wish I would ): Following the Castellemmarese War of 1930-31, Charlie Luciano coalesced the US Italian mobs around a clearly defined set of families and a family structure that had been established just a few months earlier by Salvatore Maranzano, who was assassinated on Luciano's orders. Luciano didn't publish a set of "rules" or "behaviors" for Mafia families. They didn't send away to Sicily for charter certificates in "the Mafia." Nor did they even call themselves "Mafia" officially (newspapers did that). Rather, Luciano and his colleagues agreed that competition was bad for the organized crime business, so they worked to establish monopolies on rackets in cities or neighborhoods. They also decided that it would be best to restict membership to Italians (most were all-Italian anyway), because they were most comfortable with each other; although, following Luciano's example, they drew liberally on non-Italians for advice and help.

I thanked in advance, but once again I am astounded by the fountain of all Mafia-related knowledge! Thanks Turnbull. That cleared everything up and more!

Mick

The family system is officially sanctioned. There is one Mafia family in each major city in America; except for New York, which has five families. The New York families are the most powerful.

Capone wasn't mafiosi - his group was called the "outfit".

Pretty interesting, my compliments, Turbull. It was also a very good question, one I had been meaning to ask!
So technically, if you look at it like that, no one is really mafia except the old Sicilian mafia, which went under that name. It seems as though they're all just "Italian criminals" these days.
Was there only one family in each city (with exception of New York)? No more, no small time mafia? Did they allow competition then?
Sorry guys I'm plaguing this beautiful post with my swarm-like questions!

Researcher, the question in the subject has now been answered, so feel free to post other questions.

Mick