Anyone. It's not very costly and anyone can play -- wealth, age or strength has no bearing. Many bridge players are Seniors - - but an increasing number of college-age and even high-school and grammar school kids play Duplicate. There are clubs and organization everywhere that sponsor Duplicate games, often on weekday afternoons, evenings, weekends, Holidays - - all the time in major metropolitan areas.
Handicapped People. It's wonderful for people with physical handicaps that prevent many sports and other leisure time activities, because it only requires you to be able to think. If you can't see too well or hear too well or can't get around very well -- come play duplicate bridge.
Provisions are made for handicapped players at most clubs and all tournaments. There are procedures for wheelchair-bound people to sit North/South at all sessions so they don't have to move around like those sitting East/West.
There are special 'Bidding Boxes" for those who are hard of hearing, and they are now in common use everywhere.
Duplicate players are very helpful and considerate -- but they will do anything legal to beat you a trick.
It's not different than normal bridge. If you can play bridge, you can play Duplicate. Duplicate isn't harder bridge -- it's just better bridge. Aside from learning a few rules of protocol and procedure, you can start playing Duplicate any day you want to, assuming you are now a bridge player. The scoring is a little different, in that each hand is a separate contest, and the cards aren't shuffled nor played into the middle of the table. Other than these few things, it's just good, hard bridge with other people who are serious about the game.
(c) Robert D. McConnell, 1998 All Rights Reserved