Per-and polyfluoroalkyl substances (PFAS) are of increasing concern due to potential adverse effects on human health and ecosystems. Despite their high concern, the equilibrium partition properties of PFAS remain to be elucidated. Even basic property data such as octanol/water partition coefficients (Kow) are scarce for PFAS. To my knowledge, only one scientific paper has reported measured Kow values for neutral PFAS with perfluoroalkyl chain lengths of 4 or more. Similarly, reliable air/water partition coefficients (Kaw) were available for only a few neutral PFAS with (CF2)≥4 until our group recently reported experimental values for 21 PFAS. The equilibrium partition of organic compounds is determined by the intermolecular interactions of the organic compounds with the surrounding phases, including polar (e.g., hydrogen (H)-bonding) and nonpolar (i.e., van der Waals) interactions. This study focuses on neutral compounds and neutral species of ionizable compounds, since the partitioning of ionized compounds is controlled by different mechanisms. For neutral organic compounds, polyparameter linear free energy relationships (PP-LFERs) with Abraham's solute descriptors can quantify the energetic contributions of the relevant intermolecular interactions and describe partition coefficients in general. The PP-LFER equation most applicable to PFAS appears, Log K = c + sS + aA + bB + vV + lL (1) K is the partition coefficient of interest. The uppercase letters on the right side of eq 1 are the solute descriptors: S, dipolarity/polarizability parameter; A, solute H-bond donor property; B, solute H-bond acceptor property; V, McGowan's molar volume; and L, the logarithmic hexadecane/air partition coefficient (KHxd/air) at 25°C. The lowercase letters are referred to as system parameters, are calibrated by least-squares multiple linear regression (MLR) with typically 50 or more calibration data, and reflect the complementary interaction properties of the two phases. The terms with S, A, and B describe the polar interactions, while those with V and L describe the nonspecific cavity formation and nonpolar interactions.