Self adjusting and/or locking buckle tongue assemblies for use with occupant restraint systems in vehicles are described herein. In one embodiment, a buckle tongue assembly includes a plate having a tongue portion configured to cooperatively engage a corresponding buckle assembly. The buckle tongue assembly of this embodiment can further include first and second web gripping portions carried by the plate. The second web gripping portion is configured to move relative to the first web gripping portion between a first position in which the web gripping portions are spaced apart to permit movement of a web therebetween, and a second position in which the web gripping portions are engaged or interlocked to clamp the web therebetween.