If the ball is at the point position, the middle defender is playing “on a string,” and should close the gap accordingly.  This defender must also play on a string (east-west) to the half-boards, especially on the strong-side.  Should the point player catch the ball on a skip pass, sometimes the closest high defender will have to close the gap if the player is a threat to shoot, in which case the middle defender needs to ad-lib and take over the spot (zone) where the help came from.

If the ball is at the shooter or crease positions, the closest defender in that part of the zone should pressure (man-to-man) the ball and the defender in the middle should replace their position in the box, playing a “tight” zone.  Any players not pressuring should at all times be standing in passing lanes and shooting lanes, "showing help" as much as possible (without over-committing).

Defenders in “the box” should also follow cutters until they exit their zone, and be as physical as possible when an opponent is close by.

Variation:  A more remedial ("Modified") way to play the Box + 1 Zone Defense is to only pressure the ball with the high defenders and the point player.  The low defenders should stay anchored at the crease positions, in the shooting and passing lanes, while remaining "as low as the lowest offensive player" on their side of the floor (moving north-south where required).

Variation:  Another way to play this defense is as a Box + Lock-Off, which usually sees the team's best defender "locking off" the opponents best offensive player ("denying" them the ball), both off-ball & on-ball (switching only out of desperation), while everyone else plays a "box" zone defense.