Most past studies have focused on customer retention and have overlooked the importance of customers' cross-buying behavior. The research at hand demonstrates how variables such as behavioral loyalty, firm reputation, preference for closeness, assortment composition and perceived value influence the development of customers' cross-buying intention in the context of apparel online shopping by introducing two theoretical frameworks. The first model investigates the effect of behavioral loyalty, firm reputation, preference for closeness, and perceived value on cross-buying intention. The results show that perceived value strongly influences the relationships of other variables with customers' cross-buying intention. The second model assumes different types of goods - complementary, substitution and both - to examine the effect of assortment composition on the level of cross-buying controlling for other factors (e.g. perceived value, loyalty, etc.). The results indicate that assortment composition has a greater influence on the level of cross-buying when customers are exposed to substitution and complementary products while looking for a particular product.