Twelve Caribbean species of Vachellia (formerly Acacia subgenus Acacia) are formally monographed with taxonomic, habitat, geographic distribution descriptions, and lists of representative specimens examined. The species treated here are all part of the informal Vachellia acuifera group, which is characterized by generally enlarged stipular spines borne in clusters on the stems, 1–3 pairs of pinnae per leaf, and 20–50 stamens. Ordination analyses of vegetative characters show that these species form discrete groups in two- and three-dimensional plots. Vachellia baessleria Clarke, Seigler, & Ebinger, endemic to Guantánamo and Las Tunas, Cuba, is newly described. Vachellia acuifera is wide ranging, occurring from the Bahamas to Cuba. The other species are highly restricted in their distribution and ecological setting. Four of the species are only known from Hispaniola (V. barahonensis, V. caurina, V. cucuyo, and V. oviedoensis) and six only from Cuba (V. baessleria, V. belairioides, V. bucheri, V. daemon, V. roigii, and V. zapatensis). Another species, V. anagadensis, is only found on the island of Anegada in the British Virgin Islands.