She was born and grew up on the Penticton Indian reserve in British Columbia's Okanagan Valley, and fluently speaks both the Syilx and English languages.
Armstrong identified strongly with the book "Cogewea, the Half-Blood," written by Mourning Dove, one of the earliest Native American women novelists in the United States.
Controversy has arisen as a result of misunderstandings about her claim of this Okanagan recognized relationship to Christine Quintasket aka Mourning Dove.
[10] Armstrong discovered her interest and talent for writing at age fifteen when a poem she wrote about John F. Kennedy was published in a local newspaper (Voices).
As a teenager, Armstrong continued to publish poetry and develop her literary voice by reading and listening to works by Aboriginal authors such as Pauline Johnson and Chief Dan George, who she identifies as her early influences.
The objectives of the society which governs En'owkin, as Armstrong describes, are "to record and perpetuate and promote 'Native' in the cultural sense, in education, and in our lives and our communities" (qtd in Lutz 27).
She took on the project to forestall the work of more famous non-Aboriginal authors, who were "dripping at the mouth" to document Native history (Williamson qtd in Jones 60).
Tommy has encountered intolerance in an assimilationist school system and racist North American society, but his family encourages him to be proud of his Okanagan heritage.
Armstrong has said that Slash is not a chronicle of AIM (American Indian Movement); rather, the text provides a personalized account of the origins and growth of Native activism since the 1960s (Lutz 22 and Jones 51).
Her short stories are collected in works such as All My Relations: An Anthology of Contemporary Canadian Native Fiction, edited by Thomas King.
As a campaigner for Aboriginal rights, Armstrong serves as an international observer to the Continental Coordinating Commission of Indigenous Peoples and Organizations.
In a 1989 interview with Hartmut Lutz, Armstrong relates that some feminist scholars questioned her decision to create a male protagonist for her novel Slash.
She explains that she could not isolate the character of Slash from his community in order depict his individual nature and still compose the story for her people (Lutz 16).
In her study of Slash, Manina Jones catalogues a number of critical responses to the work; she says that many academic articles relate the difficulties of readers in understanding Armstrong's novel.
Jones suggests that an innovative critical reading approach is essential to appreciate Armstrong's work and satisfy the goals of the Okanagan Indian Curriculum Project.