A method and system for installing software implementations such as applications and COM classes as they are needed from an external source, such as a centralized network store. When a software implementation is needed, the system and method first look to the local system (e.g., registry) for that software implementation, and if found, returns the information such as a local path needed to use the software implementation. If the implementation is not found locally, the present invention dynamically looks to a centralized class store of a network, to locate the needed implementation. When located, the implementation is downloaded and locally installed in a manner that is essentially transparent to the user. Software implementations such as application products may be divided into features and components to improve on-demand installation thereof.