Cross-country skiing is an endurance sport which imposes several physiological and biomechanical challenges due to the perpetual changes between, and utilisation of, different skiing techniques. In Scandinavia, the development of motor skills, speed and “athletism” starts at an early age and the on-snow training is performed on many different types of skis (XC and alpine skis, telemark and snowboard) in order to build up a broad “ski-competence”, with a gradually specialization towards the more narrow cross-country skis. Although, endurance training is of great importance in cross-country skiing it can initially be performed using a variety of endurance sports with a later specialization towards cross-country skiing starting from the junior age. Strength and roller ski training usually starts more regularly from an age of 15-16 yrs. Altogether, XC training places some special demands on coaches’ knowledge of how to optimize development of the young skier, reinforced by the great development of the sport during the last decade with new techniques and racing forms. Special ski high schools in areas with long winter and well-educated coaches has shown to be a success factor for junior skiers to take the last step on the “long and winding road” from being a young skier to become an elite skier.