Tackling in rugby is now a major cause of injury. The use of rugby shoulder pads is intended to reduce injury from front-on tackles, although the pad's ability to reduce injury has not been examined. This paper strives to present a novel method, using Tekscan sensors, for measuring in vivo impact intensities during a front-on tackle to assess the effectiveness of rugby shoulder padding in reducing peak force during impact. It was hypothesized that padding would not significantly reduce peak impact force. Rugby pads were instrumented with thin film force sensors to measure impact intensities during tackles with and without pads. Sensors were first statically then dynamically calibrated using force plate data. Results showed that the pad significantly reduced peak impact force by up to 35% when impacted with an object and by 40% overall for all tackles. The hypothesis that the shoulder pad could not significantly reduce peak force at impact was rejected, since the pad reduced peak force by 41% in tackles with a run-up and 40% overall for all tackles. However, this reduction in force was localized directly above the acromioclavicular joint, while forces in the surrounding areas were not reduced.