The online retail environment is expanding, enhancing the possibilities for customers to shop online. On the one hand, a proliferation of online channels establishes a multichannel online retailing landscape, which offers customers more alternatives in terms of where to shop online. On the other hand, a change in the user interaction mode of existing customer touchpoints, from graphics to voice, creates new voice dialog interfaces, which enhance the way with regard to how customers can shop online. In this context, this publication-based dissertation aims to generate theoretical and practical contributions on these two most recent developments in online retailing, i.e., multichannel online retailing and voice dialog interfaces, to improve marketing mix decision-making.