An L p -theory of local and global solutions to the one dimensional nonlinear Schrödinger equations with power type nonlinearities |u| α−1 u, α > 1 is developed. Firstly, some twisted local well-posedness results in subcritical L p -spaces are established for p < 2. This extends YI.Zhou's earlier results for the gauge-invariant cubic NLS equation. Secondly, by a similar functional framework, the global well-posedness for small data in critical L p -spaces is proved, and as an immediate consequence, L p ′ -L p type decay estimates for the global solutions are derived, which are well known for the global solutions to the corresponding linear Schrödinger equation. Finally, global well-posedness results for gauge-invariant equations with large L p -data are proved, which improve earlier existence results, and from which it is shown that the global solution u has a smoothing effect in terms of spatial integrability at any large time. Linear weighted estimates and bi-linear estimates for Duhamel type operators in L p -spaces play a central role in proving the main results.2000 Mathematics Subject Classification. 35Q55.