Buick 2007 Rendezvous Owner's Manual page 22

Folding or Reclining the Seatbacks
CAUTION:
{
If the seatback is not locked, it could
move forward in a sudden stop or crash.
That could cause injury to the person
sitting there. Always push and pull on the
seatback to be sure it is locked.
22
To recline the seatback, lift the recliner lever
located on the outboard side of the seatback.
Release the lever when the seatback is in
the desired position.