A hierarchical porous framework with interconnected micro- and mesopores (analogous to a tree root system) has a unique structural advantage for CO2 capture. The larger mesopores can substantially increase the accessibility of the micropores to guest molecules through enhanced diffusion. In their Communication on page 4582 ff., S. Dai and co-workers introduce a soft-chemistry synthetic strategy based on a Friedel–Crafts alkylation for the creation of such porous phenolic polymers.