Twins in marbles of Toutak metamorphic complex show a direct relationship of twin width and intensity. The transition from dominant thin twinning to dominant thick twinning occurs at temperature between 150 C and 200 C. Below the transition temperature, increasing strain is apparently accommodated by adding new twins, and above the transition temperature strain is accommodated by twin widening. Similar phenomenon was also studied in the Helvetic Alps, the prealps and the central Appalachian. These data for deformed marbles supported the interpretation from experimental studies of a temperature effect on twin width and intensity and indicate that the twinning in marbles of Toutak complex occurred at peak metamorphism.