This paper is intended to be tutorial in the specific area of lumped parameter immittance measurement at radio frequencies. Included is a brief background discussion with particular emphasis upon the important recent developments of precision coaxial connectors and coaxial air dielectric transmission lines as immittance standards. Special emphasis is given to precision coaxial connectors and their necessity in achieving highest accuracies. Other sections of the paper deal with standards, techniques of measurement, and instruments. The present state-of-the-art is presented in graphical form wherein the accuracies attainable by best practices are compared with the best capabilities found in specifications for commercial instruments. The state-of-the-art presentation includes two-terminal as well as three-terminal measurements. The paper concludes with some recommendations for improving the state-of-the-art in this measurement area.