Originally Posted by: WeslabaWell, this is how it works out... as you probably know, chords have formulas, such as, 1 3 5, 1 b3 5, etc. These are very valuable to know because, the modes also have their formulas. Ionian is 1 2 3 4 5 6 7, so this would work over a major chord, which is 1 3 5. Dorian is 1 2 b3 4 5 6 7, so, with the b3, it will work over minor chords (1 b3 5) I won't go into the other ones, because I'm not too up on the chord formulas myself, but you get the idea. Just match the formulas, and that's how it works. It's basically just memorization, unless someone knows of certain jedi mind tricks to aid the theoretically challenged such as I.

For the sake of being politically correct in this thread;
Dorian is 1-2-b3-4-5-6-b7
1-2-b3-4-5-6-7 would be the Melodic minor (Ascending).
Hope that helps................