The core planar cell polarity (PCP) complex conveys directional information across vast cell distances, generating polarized cell behaviours and structures. The complex consists of the transmembrane proteins CELSR1–CESLR3, VANGL1, VANGL2, FZD3 and FZD6, and the cytoplasmic proteins PRICKLE1– PRICKLE3 and DVL1–DVL3. The increasing availability of mouse strains carrying genomic alterations in PCP genes has greatly facilitated studies that assess the temporal and tissue-specific functions of PCP (for genetic and phenotypic details of strains, see Supplementary Table 1). When designing experiments, it is important to consider whether and how these mice could be used to answer particular scientific questions.