With the 1st pick of the 18th Round (527th overall), the Astros select 6'2" 195lb Adam Nelubowich, a Senior left-handed hitting 3B from Washington State.
Nelubowich was previously drafted by the Seattle Mariners in the 14th round in 2009, and this year hit .299/.348/.436, with 3 HR and 34 RBI in 211 AB. He also led the West Coast League in SLG (.490), HR (8), and RBI (36) back in 2011, playing for the Wenatchee AppleSox.
Jonathan Mayo says this:
"Nelubowich was drafted in the 14th round in 2009 and it remains to be seen if he has improved his Draft stock enough to go higher this time around. Defensively, the redshirt junior has a good arm and soft hands at third but lacks agility, leading many scouts to project a move to left at the next level. He has a loose, handsy swing at the plate and has some power potential but doesn't have a great feel for hitting."
His Washington State bio page is here.