This practices and experience paper describes the coordination, design, implementation, availability, and performance of the Pacific Rim Applications and Grid Middleware Assembly (PRAGMA) Grid Testbed. Applications in high-energy physics, genome annotation, quantum computational chemistry, wildfire simulation, and protein sequence alignment have driven the middleware requirements, and the testbed provides a mechanism for international users to share software beyond the essential, de facto standard Globus core. In this paper, we describe how human factors, resource availability and performance issues have affected the middleware, applications and the testbed design. We also describe how middleware components in grid monitoring, grid accounting, grid Remote Procedure Calls, grid-aware file systems, and grid-based optimization have dealt with some of the major characteristics of our testbed. We also briefly describe a number of mechanisms that we have employed to make software more easily available to testbed administrators.