Electrophoretic deposition is used to deposit CdS and CdSe nanorods onto planar centimetre scale substrates directly from solution. It is found that the net charge and dipole interactions on the nanorods are the sole factors in the resulting assemblies formed upon deposition, with the higher net charge nanorods forming vertically aligned assemblies, while the nanorods with a reduced net charge forming horizontal assemblies. Numerical modelling and simulation provided an insight into the resulting deposits and it was concluded that a minimum net charge of +4e is required to obtain vertically aligned assemblies. This significant result means that nanorods can be tailored for specific device architectures by modification of the nanorod such as net charge, with vertically aligned assemblies being ideal for sandwich-type structures and horizontally aligned assemblies being ideal for planar electrode-type optoelectronic devices. (C) 2015 The Electrochemical Society. All rights reserved.