The impact of very precise CLAS and COMPASS g 1 /F 1 data on the polarized parton densities and higher twist effects is discussed. It is demonstrated that the inclusion of the low Q 2 CLAS data in the NLO QCD analysis of the world DIS data improves essentially our knowledge of HT corrections to g 1 and does not affect the central values of PDFs, while the large Q 2 COMPASS data influence mainly the strange quark and gluon polarizations, but practically do not change the HT corrections. The uncertainties in the determination of polarized parton densities are significantly reduced due to both of the data sets. These results strongly support the QCD framework, in which the leading twist NLO pQCD contribution is supplemented by higher twist terms of O(Λ 2 /Q 2 ). Different solutions for the polarized gluon density, as well as the present status of the proton sum rule are also discussed.