[4] The family has a subcosmopolitan distribution, ranging from the subarctic to the southernmost parts of Africa, Australia, and South America.

[10] Today, most authors recognize at least 25, but this number will change because some of these genera have recently been shown to be polyphyletic.

In spite of the sparsity of the fossil record, and the inaccuracy of molecular-clock dating, it is clear that Oleaceae is an ancient family that became widely distributed early in its history.

Some of the genera are believed to be relictual populations that remained unchanged over long periods because of isolation imposed by geographical barriers like the low-elevation areas that separate mountain peaks.

Alternate or whorled arrangements are rarely observed, with some Jasminum species presenting a spiral configuration.

The obvious feature that distinguishes Oleaceae and its sister family, Carlemanniaceae, from all others, is the fact that while the flowers are actinomorphic, the number of stamens is reduced to two.

Forsythias, lilacs, jasmines, osmanthuses, privets, and fringe trees are valued as ornamental plants in gardens and landscaping.

For example, Antoine Laurent de Jussieu, in his Genera Plantarum in 1789, placed them in an order which he called "Jasmineae".

[17] The last revision of Oleaceae was published in 2004 in a series entitled The Families and Genera of Vascular Plants.

Since that time, molecular phylogenetic work has shown that the next revision of Oleaceae must include substantial changes to the circumscription of genera.

[7] Oleaceae is one of only a few major plant families for which no well-sampled molecular phylogenetic study has ever been conducted.

The only DNA sequence study of the entire family sampled 76 species for two noncoding chloroplast loci, rps16 and trnL–F.

Little was determined in this study, largely because the mutation rate in the chloroplast genome of Oleaceae is very low compared to that of most other angiosperm families.

[21] The genus Ligustrum has long been suspected of having originated from within Syringa, and this was confirmed in a cladistic comparison of selected chloroplast genes.

[23] Chionanthus is highly polyphyletic, with its species scattered across the phylogenetic tree of the subtribe Oleinae.