The linear peptide Y-Q-N-P-D-G-S-Q-A (one letter amino acid code) displays a high population of P-hairpin conformations in aqueous solution at 5 degrees C (F. J. Blanco et al. J. Am. Chem. Sec. 1993, 115, 5887-5888), indicating that it should be a useful model system for elucidating local interactions that induce and stabilize beta-hairpins. Against this background, we have performed a detailed study of the peptide’s conformational and dynamic properties using 2D NMR and computational modeling. Using the linear component of NOE buildup curves, 122 nuclear Overhauser effect (NOE) distance constraints were derived for the major (trans-Pro-4) isomer. These distance constraints and three dihedral angle constraints were used in conjunction with simulated annealing (X-PLOR program) to produce a well-converged set of 24 solution structures.