Tensile test failure lines across 15 mm wide strips of uncalendered newsprint were found to pass largely through areas of below average grammage. The breakline in commercially calendered newsprint passed largely through areas of above average grammage. At intermediate degrees of calendering both higher and lower than average grammages were involved. Tensile tests of 0-5 mm wide calendered newsprint samples also showed an inverse relationship between strength and grammage. The number of sulphite fibres and their angles to the machine-direction of the paper (the straining direction) were also shown to influence tensile strength.