HITECH and the subsequent Meaningful Use criteria means HIE activity will become more widespread in the near future. However, healthcare professionals must actually use the information systems that make the information from HIE activities available before any benefits can accrue. This study provides insights into some of the general reasons for, and barriers to, HIE usage for pediatric emergency encounters. First, as anticipated, factors suggestive of more complex patients were associated with both basic and novel usage. Specifically, the more conditions present at the encounter and recent hospitalizations increased the odds of usage. Both of these factors are consistent with HIE usage research in adult populations,[26,41,42] and complex situations, in general, are a driver of information seeking [43]. Likewise, frequent primary care usage increased the odds of both basic and novel HIE usage. Patients with numerous encounters in other settings create interdependencies in the provision of care and increased information about those encounters could prove useful in patient care. However, the frequent use of other services may also be an indicator of ill health and therefore complexity.