Abstractclass of Laminar Proportional Amplifiers (LPA's) Is presented. The LPA Is a pressure controlled proportional fluid amplifier which operates with its power jet In the laminar flow regime. The mathematical model for the Input characteristics of the LPA Is based on a lumped parameter analysis of the input flow fleld when the supply jet is In the centered (i.e. null) position. The resulting flow equations are then linearized for the Input characteristics when the jet is deflected due to a lateral pressure gradient. In addition to the null and deflected-jet Input characteristics, an experesslon Is also developed for the degree of cross-coupling existing between the control ports. The analytical results are compared to experimental data and good agreement is found to exist.