In this paper, we identify some of the fundamental issues that must be addressed in designing a desktop Experiment Management System (EMS). We develop an abstraction of the set of activities performed by scientists throughout the course of an experimental study, and based on that abstraction we propose an EMS architecture that can support all such activities. The proposed EMS architecture is centered around the extensive use of conceptual schemas, which express the structure of information in experimental studies. Schemas are called to play new roles that are not usually found in traditional database systems. We provide a detailed exposition of these new roles and describe certain characteristics that the data model of the EMS must have in order for schemas expressed in it to successfully play these roles. Finally, we present the specifics of our own effort to develop an EMS, focusing on the main features of the data model of the system, which we have developed based on the needs of experiment management.