Sister Wilhemina was born in St. Louis as Mary Elizabeth Lancaster on April 13, 1924, the second of five children of Oscar and Ella Lancaster.
According to
an autobiography shared by the religious order she founded, in 1934, when she was nine, she took First Communion, later writing that she experienced a vision in which 'Our Lord asked me if I would be His.'
'He seemed to be such a handsome and wonderful Man, I agreed immediately,' she wrote. 'Then He told me to meet Him every Sunday at Holy Communion. I said nothing about this conversation to anyone, believing that everyone that went to Holy Communion heard Our Lord talk to them.'
Growing up in segregated St. Louis was not without adversity for young Lancaster, and according to CNA, she was once taunted with the racist nickname 'chocolate drops' as she passed through a white neighborhood on her way home from school.
When the local Catholic high school became segregated, Lancaster's parents, who did not want her to attend public school, founded St. Joseph's Catholic High School for Negroes.
She graduated as valedictorian of the school her parents had helped to found, and then entered training with the Oblate Sisters of Providence in 1941.
On March 9th, 1944, she took her vows of poverty,