Sister Marielena was missioned to Venezuela, where her first assignment was with the cottage industry program at Hospital Coromoto. In 1973, she decided to move into Barrio Simon Bolivar, one of hundreds of slum areas around Maracaibo. Here she found rows of cardboard houses with tin roofs, dirt roads, and no sewage system.

Together with a group of residents, a Jesuit priest, and a Jesuit student, Sister Marielena helped form a Christian cooperative in the barrio. "In order to support even the most fundamental elements of human existence, the inhabitants of a barrio need to have some form of organization," she explains. "It needs to embody the life, aspirations, and hopes of the people."

In 1980, Sister Marielena became co-director of the center for socio-political formation, Domingo Verde, which gave conscientization classes to help the barrio residents realize their personal and communal potential. In 1986, the Domingo Verde Center opened, allowing for weekend seminars. Sister Marielena has stayed active in the Center as it grew. In 2005, the Center coordinated formation programs for 240 organizations.

"The face of the barrio has changed, and a whole lot else too," says Sister Marielena, citing many improvements over the past 33 years. She continues to participate in the regional coordination of Basic Christian Communities, and she enjoys working with children preparing for First Communion.