While there, she came under the influence of the father of modern ethnobotany, Richard Evans Schultes, to whom she attributes a lifelong interest in botany and ecology, themes which often appear in her novels and poetry.

[6] She also founded the CSUS English Department Graduate Creative Writing Program along with poet Dennis Schmitz and novelist Richard Bankowsky.

In 1978 Mackey founded The Feminist Writers' Guild with poets Adrienne Rich and Susan Griffin, author Charlene Spretnak, and novelist Valerie Miner.

Set in Europe in the Neolithic Period, they deal with struggles between matristic earth-centered goddess-worshiping cultures and invading patriarchal nomads.

Mackey's Season of Shadows is set at Harvard in the late 60's and deals with various political issues such as the Civil Rights Movement and protests against the United States' involvement in the Vietnam War.

In 2003 and 2004, in a departure from her previous styles and themes, Mackey chose to write The Stand-In and Sweet Revenge under the pen name "Kate Clemens."

Critics have called it "fierce," "surreal," "ecstatic," "passionately transcendent," and "corrosive," and noted her "hallucinatory troping" which is "continually deconstructing rational consciousness.

In 2011, Marsh Hawk Press published Mackey's sixth collection of poetry, Sugar Zone which won the 2012 PEN Oakland/Josephine Miles Literary Award.

Mackey has said that many of her poems are inspired by the extremely high fevers she has experienced on multiple occasions and by the works of Brazilian novelists and poets, noting that often they "combine Portuguese and English as incantation to evoke the lyrical space that lies at the conjunction between the two languages.