>>To stop it, set AutoSize=.F.
>
>But I was hoping to have autosize set to .T. so that when the caption changes (and it will) it could simply grow to the left but keep its right side fixed at its initial position. Can this be done?

Try

Thisform.label1.Caption = "New Caption"
Thisform.label1.AutoSize = .T.
Thisform.label1.AutoSize = .F.