Following our previous study on the stereoselective cocrystallization of linear and cyclic dicarboxylic acid residues in copolyamides 12.6/12.1,4-cyclohexanedicarboxylic acid (12.6/12.1,4-CHDA, Vanhaecht et al., Macromolecules 2004, 37, 421), we have now investigated a series of copolyamides containing trans or cis isomers of 1,4-diaminocyclohexane (1,4-DACH), viz. 4.14/1,4-DACH.14. Solidstate NMR studies and WAXD experiments demonstrate that the cis isomer is present in the amorphous regions of the copolyamide, whereas the trans isomer is located in both the crystalline and the amorphous phase. Similar to the results for the trans-1,4-CHDA-based copolyamides, trans-1,4-DACH moieties are probably built into the crystalline structure with the cycloaliphatic ring oriented perpendicular to the hydrogen-bonded crystal sheets. Temperature-dependent WAXD patterns show that, unlike in the homopolyamide 4.14, a pseudohexagonal phase is not formed at the Brill temperature in the copolyamide. Instead, crossing rather than merging of the (100) and the combined (010)-(110) WAXD reflections occurs upon heating of the copolyamides containing trans-1,4-DACH. In contrast to the cis isomer, introduction of trans-1,4-DACH into polyamide 4.14 raises the melting temperature, confirming the findings by solid-state NMR and WAXD analysis. Unlike 1,4-CHDA moieties, 1,4-DACH residues do not undergo thermal isomerization. Therefore, at the same amount of initially trans isomers, the copolyamides 4.14/1,4-DACH. 14 exhibit higher second heating end melting points than the corresponding isomeric copolyamides 12.6/12.1,4-1,4-CHDA.