Rubuta ci gaba don wannan sakin layi - Karff ta taka leda a gasar zakarun duniya na mata guda uku: 1937 Stockholm, tana wasa da Falasdinu kuma ta sanya ta shida (wanda Vera Menchik ya ci nasara); 1939 Buenos Aires, tana wasa da Amurka kuma ta sanya ta 5 (wanda Menchik ya ci nasara); 1949 Moscow
, wasa don Amurka (wanda Lyudmila Rudenko ya lashe). Lokacin da FIDE ta kafa lakabi a 1950, Mona May Karff na ɗaya daga cikin matan Amurka uku da suka karɓi taken Mace Mace ta Duniya.