What is a typical European Waltz chord progression?

Question

The kind in european folk music with accordions.

Answer 1

That's a very general question, which could refer to a lot of different types of music.  But by and large because the waltz genre is usually popular in nature, and furthermore is often used for dancing to, the harmonies will mostly be quite simple.  You can expect most examples to rely heavily on alternations between I and V, with occasional surprises such as brief changes to the relative minor (again mostly focussing on i and V within that key as well), interrupted cadences (e.g. I - V - vi) etc.

The nature of the accordion is such that fairly standard progressions are easiest, since it has buttons for each of the standard chord types of augmented, major, minor, and diminished.  So a general progression applicable both to waltzes and many other genres could look like this: I - IV - I - V - vi - ii - V - I.  The basic idea is that I and V are the most important chords, so your progression is going to start with I, possibly move through some other chords and end up on V, then resolve back to I.  Usually you'd want any return to I to be preceded by either IV or V, since those give the strongest sense of cadence, and moving from other chords to I can give you fairly unorthodox effects.  

As far as when to press which button is concerned, in major keys I, IV and V are major, ii, iii and vi are minor and vii is diminished.   In minor keys (though this depends on whether you're using the harmonic, melodic ascending or melodic descending version; these chords are for the harmonic minor), V and VI are major, i and iv are minor, ii and vii are diminished and III is augmented.  Happy waltzing!