[1] In the cladogram below,[2] the small, closely related families in bold at the ends of the branches are covered in separate articles.

[3] The pronouns Ross reconstructs for proto-Sepik are:[4] Note the similarities of the dual and plural suffixes with those of the Torricelli languages.

[3] In contrast, languages within the Ramu, Lower Sepik, and Yuat families all have relatively uniform typological profiles.

In some languages, objects can be classified as either masculine or feminine, depending on the physical characteristics intended for emphasis.

[3] Many Sepik languages from different branches, including Awtuw, May River Iwam, Abau or Alamblak, encode periodic tense in their verbal morphology, though the markers themselves are not cognate.