The present invention provides Ligand-Drug Conjugates comprising a PEG Unit in a parallel orientation to the Drug Unit. The invention provides inter alia, Ligand-Drug Conjugates (LDCs), methods of preparing and using them, and intermediates thereof. The Ligand-Drug Conjugates are stable in circulation, yet capable of inflicting cell death on targeted cells or inhibiting proliferation of targeted cells once its drug cargo is released in the vicinity or within targeted cells. In principle embodiments, an LDC of the present invention is represented by the structure of Formula I.