EXCLUSIVE

"Teen Mom 2" star Adam Lind's still got some growing up to do ... because he's a wanted man for all the wrong reasons.

The Minnehaha County Sheriff's Department in South Dakota tells TMZ ... there's an active warrant for Adam's arrest for allegedly failing to pay child support. The warrant was issued on Valentine's Day.

We checked with the state office that handles these matters and we're told Adam was in the hole after 2 separate judgments were handed down last September -- one for $12,365 and another for $8,757.