As the Hubble Space Telescope (HST) moves into its Second Decade of observations, we are embarking on bringing our Phase I submission system into the 21st Century as well. Proposing for Hubble Space Telescope (HST) observing time and archival research proceeds in two phases. In Phase I, the scientific merits of the proposal are considered. Only accepted proposals enter Phase II, where the observations are specified in complete detail. With the advent of state of the art technology and the excellent prototyping work that has brought the Astronomer's Proposal Tool (APT), formerly the Scientist's Expert Assistant (SEA), from a concept 3 years ago, to an approved Project for implementation, at the Space Telescope Science Institute (STScI). We plan to make HST's Phase I submission system to be an integral part of the APT. We have always tried to maintain our Phase I strategy of keeping the interface simple, as well as having a minimal learning curve. This strategy will be maintained in the APT framework as well. In this paper we will present our concept for the Science definition, and Phase I proposal development and submission tools. We also discuss how we are transforming our current Call for Proposals (CP) document into a smaller and more concise electronic document that will address our policies and submission process. This document will be built and maintained using innovative tools and XML. We will provide links to existing documentation as well as provide all of the relevant information available via the tool as on-line 'context- sensitive' help.