Abstract: Techniques are described for determining personalized category-based product information for a user. The described techniques may in some situations be used by or on behalf of an online retailer to determine a sorted order of at least some products within a product category for the online retailer to display to a customer user on a category-specific Web page of the online retailer, such as based on a browse request by the customer for that category or on another identification of the category by the customer. The determination of particular personalized category-based sorted products for such a customer may in some situations be performed based at least in part on prior activities of the customer, including prior interactions by the customer with the online retailer (e.g., actions by the customer to view and/or purchase particular products, product brands, product sub-categories, product sizes, etc.).