Yes, it has a headphone jack. And I think it is 3.5mm. I've only ever used one size of headphones. They do sell headphones specifically for the Leappad2, but my earbuds for my iphone fit it also. Hope that helps!
Yes, it has a headphone jack, and Leapfrog also makes kid friedly headphones for it. But it has a volume control built in...what kids toy now-a-days doesn't have sound effects and animated voices anyway???