Apparatus and methods for envelope shaping in power amplifier systems are provided. In certain implementations, a power amplifier system includes a modulator for generating a RF signal, a power amplifier for amplifying the RF signal, a gain control circuit for controlling the gain of the power amplifier, and an envelope tracking system for controlling a voltage level of the power amplifier's supply voltage based on an envelope signal corresponding to the RF signal's envelope. The gain control circuit includes a gain adjustment table, and the envelope tracking system includes an envelope shaping circuit including an isodistortion table. The isodistortion table can be used to map the envelope signal to a shaped envelope signal so as to maintain a substantially constant distortion in the system's transmit and/or receive bands across the envelope signal's range.