In the classification system of Dahlgren the Fabales were in the superorder Fabiflorae (also called Fabanae) with three families corresponding to the subfamilies of Fabaceae in APG II.

Research in the order is largely focused on the Fabaceae, due in part to its great biological diversity, and to its importance as food plants.

[3][4] While taxonomists using molecular phylogenetic techniques find strong support for the order, questions remain about the morphological relationships of the Quillajaceae and Surianaceae to the rest of the order, due in part to limited research on these families.

[5] According to molecular clock calculations, the lineage that led to Fabales split from other plants about 101 million years ago.

[6] The Fabales are a cosmopolitan order of plants, except only the subfamily Papilionoideae (Faboideae) of the Fabaceae are well dispersed throughout the northern part of the North Temperate Zone.