In these proceedings we present a brief summary of the parallel Session IV, ``Neutrino masses, states and interactions'', part of the Neutrino Oscillation Workshop 2018.
Topics of the session included the current status of some experimental searches for the neutrino absolute mass scale, a resume of recent results and developments in neutrinoless double beta decay, the situation of the search for a light sterile neutrino with a mass around 1 eV, a phenomenological summary on neutrino electromagnetic properties and a discussion about theoretical models for neutrino masses and mixings.