The Arginine Feasibility project was funded as part of an R34 clinical trials planning grant that will establish a protocol steering committee with expertise in Sickle Cell Disease (SCD) clinical trials, create a clinical network of sites with a strong track record of successful participation in multi-center trials, create an ED-based pain protocol, develop a data coordinating plan, identify safety and clinical endpoints and a completed protocol for a phase III clinical trial of L-arginine for the treatment of vaso-occlusive pain in children with SCD to be submitted for NIH funding. Specifically this study is creating a standardized ED-based pain therapy protocol based on NIH guidelines that will be utilized in the future phase III trial, collecting feasibility data on volume, time of visit and admission rates from high-volume PECARN and non-PECARN sites on all potentially eligible patients with SCD and collecting demographic and clinical data through a 20 patient chart review at each participating site. This study is funded through the NHLBI.