Non-human animal cells and non-human animals comprising a humanized Asgr1 locus and methods of using such non-human animal cells and non-human animals are provided. Non-human animal cells or non-human animals comprising a humanized Asgr1 locus express a human ASGR1 protein or an Asgr1 protein, fragments of which are from human ASGR1. Methods are provided for using such non-human animals comprising a humanized Asgr1 locus to assess in vivo efficacy of human-ASGR1-mediated delivery of therapeutic molecules or therapeutic complexes to the liver and to assess the efficacy of therapeutic molecules or therapeutic complexes acting via human-ASGR1-mediated mechanisms.