For the purpose of this study, the form of Rebif® New Formulation (RNF) will differ slightly from the one you currently receive. RNF will be supplied in pre-filled cartridges containing three doses of 44mcg / 0.5 ml IFN-β-1a. This is the amount required for you to administer during the course of one full week of treatment. The dosage of RNF 44mcg is injected under the skin three times per week. The RebiSmart™ device will be provided for the administration of RNF. RNF should be administered, if possible, at the same time (preferably in the late afternoon or evening) on the same three days (e.g. Monday, Wednesday, and Friday), with at least 48 hours break between each administration. You will be asked to record the time and date of each injection in the diary cards provided. You will be taught how to properly use the device to inject the medication. You will also be reminded to rotate injection sites and advised on the importance of avoiding already inflamed areas for future injections.