  This paper gives a summary of selected highlights discussed in the working
group on "Structure Functions and Parton Densities" (WG1) at the DIS 2017
conference. From the many talks presented we extract some general themes
discussed with respect to global PDF fits, new PDF-sensitive measurements from
the LHC experiments and elsewhere, exploitation of new ideas, tools to perform
PDF fits, PDFs of heavy nuclei, and finally progress in basic theory
calculations.
