Following its resolution by diastereomeric complexation, 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane (TTSBI) was used to synthesize a chiral ladder polymer, (+)‐PIM‐CN. (+)‐PIM‐COOH was also synthesized by the acid hydrolysis of (+)‐PIM‐CN. Following characterization, both (+)‐PIM‐CN and (+)‐PIM‐COOH were solvent cast directly into semipermeable membranes and evaluated for their ability to enable the selective permeation of a range of racemates, including mandelic acid (Man), Fmoc‐phenylalanine, 1,1′‐bi‐2‐naphthol (binol), and TTSBI. High ee values were observed for a number of analytes, and both materials exhibited high permeation rates. A selective diffusion–permeation mechanism was consistent with the results obtained with these materials. Their high permeability, processability, and ease of chemical modification offer considerable potential for liquid‐phase membrane separations and related separation applications.