The work discussed in this thesis aimed to investigate the interstellar polarization law [p(lambda)/p[max] = exp (-K 2n[2]([lambda]max/(lambda)] and the behaviour of its characteristic parameters, K and lambda[max], in both max simple and complex cloud situations, i.e. for stars exhibiting rotation of polarization position angle, theta(lambda). As the law is difficult to deal with analytically, the work is here mainly based on numerical investigations. Chapter 1 contains a general review of starlight polarization including intrinsic linear and interstellar linear and circular forms but the main theme concentrates on interstellar linear polarization. In Chapter 2 existing data have been refitted to the interstellar polarization law using the method of the least squares. In Chapter 3 a numerical investigation has been made of the effect that noisy data have on deduced parameters such as K and lambda[max]. Chapter 4 contains a brief review of data for stars showing theta(lambda) with discussions of the different cloud models, especially Martin's Two-Cloud model. In Chapter 5 numerical investigations are presented of the Two-Cloud model with analysis of the results for different configurations of the two clouds. A general summary is placed at the end of the thesis
