Do all pentecostal christians believe in "speaking in tongues"?

I have made a new friend, who is pentecostal. I'm wondering if he believes in it because I've heard of it (I do not believe in it, I'm an evangelical christian). Do ALL pentecostals believe/take part in this? Thanks for any info. I want to educate myself so I don't offend my new friend, this is why i ask. Thanks.