A swell idea! The guest-responsive reversible swelling and fluorescence enhancement of a dynamic, microporous polymer network is presented. Guest-induced breathing of hydrophobic pores imparts multi-functional properties, such as super-absorbency, phase-selective swelling of oil from water and encapsulation of C 60 (see figure), to this soft micro-porous organic polymer. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.