The combination of the advantageous properties of molecular and solid catalysts is considered the “Holy Grail” in catalysis research. Great potential is provided by nanoporous polymers. Chemically well-defined moieties in combination with a high stability render these materials suitable as catalyst supports for liquid-phase and even aqueous-phase catalytic processes, especially regarding the transition from fossil resources to renewable resources. In this Minireview, recent developments are summarized, covering the three main approaches: solid metal-free organocatalysts, immobilized molecular catalyst species, and supported metal nanoparticles and clusters. Their potential is evaluated and the question as to whether nanoporous polymers can bridge the gap between homogeneous and heterogeneous catalysis is critically discussed.