Passive components for use in planar Monolithic Microwave Integrated Circuits (MMICs) based on High Electron Mobility Transistors (HEMTs) on indium phosphide substrates are presented. Design; fabrication; and modeling issues of capacitors; resistors; inductors; transmission lines; via holes; and air bridges have been addressed. Sputtered thin films have been utilized to make metal-insulator-metal (MIM) capacitors and thin film resistors (TFRs). Silicon dioxide and silicon nitride MIM capacitors exhibited capacitances from 100 to 300 pF/mm2 and tantalum nitride TFRs sheet resistivities of 80-85 ohms per square. Our microstrip transmission line fabrication technology has been utilized to make multi-turn; air bridged spiral inductors spanning from 0.5 nH to 4 nH. Air bridges and ground via holes have been used for connection and testing purposes. Scattering (S-) parameters; from 5 to 48 GHz; of all fabricated components have been measured and scalable models for CAD purposes investigated.