[1] Early in life, Killen had begun to take an interest in the temperance cause, joining the local Band of Hope.

[1] After her marriage in 1893, Killen entered actively into the work of the WCTU of Felton, and served that organization in various official positions.

In 1908, she was made president of the city Union, an office which she held for eight years; and from 1916, she was recording secretary.

In 1923, she was elected vice-president of the Delaware State WCTU, and after a year's service, she succeeded to the presidency, which office she continued to hold at least until 1928.

[3] Even in later years, she remained active in Delaware State Union work, being referred to as Honorary president.