Baseball hits top or face of screen in front of bleacher wall and bounces back on playing field -- In Play

Baseball hits top of screen and drops between screen and wall -- Home Run

Baseball hits screen and bounces into bleachers -- Home Run

Baseball sticks in screen in front of bleachers -- Double

Baseball sticks in vines on bleacher wall -- Double

Baseball comes out of vines -- In Play

Baseball hits leftfield or rightfield foul markers above painted mark -- Home Run

Baseball hits foul markers below painted mark and bounces back on playing field -- In Play

Baseball goes under grates in leftfield or rightfield and remains there -- Double

Baseball goes in or under grates on either side of home plate and remains there:
-- Pitched Ball- One Base
-- Thrown Ball - Two Bases

Also: Players cannot enter the dugout steps at Wrigley Field to catch any foul pop fly.