Distinguishing among the different etiologies of interstitial lung disease (ILD) can be challenging. This sunrise seminar will seek to review basic serologies used in rheumatology, which serologies may be useful to ask and in which cases to use them in the context of ILD investigation as well as how to discriminate meaningful from unspecific serologic features during the investigation of ILD, looking for connective tissue disease associated-ILD or other forms of autoimmune associated-ILD. The session addresses the challenges such a diagnosis can bring and propose tools and clues to help the pulmonologists in their evaluation of such cases.