The growing interest in lithium (Li) diffusion for the determination of timescales of magmatic events increases the necessity to better understand Li diffusion in common mineral phases. In this context we analyzed Li diffusion in plagioclase, one of the most common mineral phases. Our study is the first to confirm two diffusion mechanisms for Li in plagioclase, and our results indicate timescales derived from Li diffusion data in previous studies were underestimated by a factor of up to 100.