I'm once or twice a week. I find that if I wash it too frequently, my hair becomes frizzy and flyaway, so every 4 or 5 days seems to work. BUT, I should also point out that I do also wash my hair less frequently because it's dyed red, and that color loses its vibrancy very quickly when washed.

I'm guessing my hair isn't as greasy as some others, and my color definitely isn't as permanent. :)

Because I'm lazy, I always use a combination 2-in-1 shampoo conditioner, so I condition every time I shampoo it.