Length-dependent helical propensities w(Ala)(n, T) at T = 10, 25, and 60 degrees C are assigned from t/c values and NMR C-13 chemical shifts for series 1 peptides TrpLys(m)Inp(2)(t)Leu-Ala(n)(t)LeuInp(2)Lys(m) NH2, n = 15, 19, and 25, m = 5, in water. Van't Hoff analysis of w(Ala)(n, T) show that alpha-helix formation is primarily enthalpy-driven. For series 2 peptides Ac-Trp Lys(5)Inp(2)(t)Leu-(beta)AspHel-Ala(n)-beta-(t)LeuInp(2)Lys(5)NH(2), n = 12 and 22, which contain exceptionally helical Ala n cores, protection factor-derived fractional helicities FH are assigned in the range 10-30 degrees C in water and used to calibrate temperature-dependent CD ellipticities [theta](lambda), (H), (n), (T). These are applied to CD data for series 1 peptides, 12 <= n <= 45, to confirm the w(Ala)(n, T) assignments at T = 25 and 60 degrees C. The [theta](lambda), (H), (n), (T) are temperature dependent within the wavelength region, 222 +/- 12 nm, and yield a temperature correction for calculation of FH from experimental values of [theta](222), (n), (T), (Exp).