The reported rate of unsuccessful spinal taps in children is high. At the Children's Hospital of Philadelphia (CHOP), quality improvement data demonstrates a failure rate of ~40-50%. Research has shown that bedside ultrasound can improve visualization and improve the success rate of spinal taps. Increasing the proportion of successful spinal taps in the emergency department could significantly reduce the rate of unnecessary hospitalizations, additional interventional procedures and antibiotic use. Our objective is to determine if bedside ultrasound-assisted site marking will increase the proportion of first attempt successful spinal taps. This will be a prospective, randomized controlled study that will take place over the course of 18 months with the goal to recruit a sample of approximately 128 patients. We will recruit subjects from the CHOP Emergency Department. The patients will be randomized into an ultrasound-assisted group versus a non-ultrasound-assisted group. Our hypothesis is that bedside ultrasound-assisted site marking will increase the number of successful spinal taps.