In recent years there has been a trend to reduce the physical size of the sensors used in the semiconductor manufacturing industry. Because of the great utility of the Bayard-Alpert ionization gauge in this industry, it is natural for gauge manufacturers to ask: Can we retain its basic three-element design, operating voltages, good sensitivity, and low x-ray limit and, at the same time, significantly reduce its size? The answer is yes. This talk will introduce the basic concept that motivated a dual-collector design and will then trace the development of the miniature gauge based on this concept. Some details of the design were guided by use of a modeling program, and examples of ion and electron trajectories computed using this program will be shown. Experimental testing of prototypes, in conjunction with modeling, was used to select other design parameters such as filament length, collector diameter, and grid end geometry. Experimentally-determined test results for sensitivity and x-ray limit will also be presented. While no single design factor appears to dominate the gauge's performance, the combination of design choices has resulted in a gauge with good sensitivity as well as a significantly smaller size.