Solution-processable n-type ladder-based polymers are highly desirable due to their potential capability to form strong. pi-pi interactions. A series of 5 highly soluble naphthalene diimide (NDI) polymers are presented, differing in the degree to which they are able to form imine-bridged ladder polymer structures. Average electron mobilities as high as 0.0026 cm(2) V(-1) s(-1), which show an electron-mobility improvement of 4 orders of magnitude following ladderization, and on/off current ratios on the order of 10(4) are reported for the novel material PNDI-2BocL, an alkyl-substituted poly(benzoquinolinophenanthrolinedione). The structure property relationship of the aforementioned series of copolymers is presented and discussed as it pertains to organic field-effect transistor (OFET) performance.