The need for critical care information systems (CCIS) and movement away from paper-based legacy systems is increasingly well documented. Moreover, there is increasing awareness of the importance of evaluating and measuring the impacts of these systems. On the other hand, recent evaluation studies have provided little information useful to the healthcare team in evaluating CCIS in practice. A CCIS is expected to have many direct benefits, such as increased user satisfaction and increased documentation efficiency, accuracy, and quality. Texas Children's Hospital (TCH) has designed, developed, and implemented a rigorous longitudinal evaluation methodology, having broad clinical applicability, which is used to document the impact, strengths, and limitations of the Picis Critical Care Information System in its critical care units.