This paper offers a comprehensive examination of how affect and affective languages work in the poetry of Joy Harjo, particularly focusing on her 1990 poetry collection, In Mad Love and War. After briefly summarizing important concepts of affect theory, this paper presents affect as closely associated with bodily functions that influence and produce emotional responses of a subject who interacts with other subjects and particular circumstances. Many poems in In Mad Love and War such as “Grace,” “Deer Dancer,” “Bird,” “A Hard Rain,” “City of Fire,” “Nine Below” represent various aspects of affective functions that include the encounters and collisions between the individual subjects, the interactions between the individual subject and the collective subject, and the relationship between the subject and language. This work, however, is not intended to support a simplified analysis or easy application that fits the poetry of Harjo with the particular identity of Native American into the framework of the mainstream theory of affection. To avoid such a one-side approach, this paper specifically examines the intersections between important concepts of affect theory and Harjo’s poems in the context of feminist perspectives, Native worldview and colonial history.