Hi FBG--

In Argentina, "vos" is equivalent to the use of "tu" in Spain. The best example in another language that I can think of is the german usage of "Sie" and "Du".... with the Argentine equivalents being "Usted" and "Vos".

Even though everybody will understand if you use the Spanish "tu", in Argentina the usual word is "vos".

How do you know when to use "Usted" instead of "vos"? It depends on how formal you wish to be in your speech. The usual norm is that you would use the more formal "Usted" with someone that is older than you, someone that you do not know well enough, or someone with whom you would rather remain at distance. You normally use "vos" with your friends/family and "Usted" with a client.

Of course, as with most forms of language all over the world, nowadays the informal "vos" is being used more and more... even in situations where one would (in the past) never have thought of saying anything but "Usted".

Ultimatetly, it will be a judgement call on your part. Whats important for you to remember, however, is that most Argentines will not mind if you use either forms as they will appreciate that you are learning the language and trying hard to communicate, which will get you a lot of leeway and flexibility. I dont think you need to be worried about folks feeling patronized for a minor "mistake" in the use of vos/usted.