alpha(s) determination from event shapes at DELPHI

Recent studies of the strong coupling alpha(s) using the DELPHI detector at LEP [1,2] are reviewed. For the updated analysis of the data at root s = M -Z, a large number of shape observables and their dependence on the event o rientation are measured and compared to theoretical calculations in O(alpha (s)(2)). The adjustment of the renormalization scale mu turns out to be of major importance. Applying the so-called physical scale mu(2) = Q(2) leads to a poor description of the data, whereas a combined fit of alpha(s) and t he renormalization scale value yields an excellent description of the high statistics data. For these scale values perfect consistency of the fit valu es of alpha(s)(M-Z) is obtained for all the observables considered within a range of Delta alpha(s) = +/-0.0025. Taking also account of heavy quark ma ss effects yields the preliminary result alpha(s)(M-Z(2)) = 0.117 +/- 0.003 . Additional studies include an alpha(s) determination using theoretical pr edictions in the next to leading log approximation (NLLA), matched NLLA and O(alpha(s)(2)) predictions as well as theoretically motivated optimized sc ale setting methods. The running of alpha(s) is measured from the DELPHI da ta at root s = 130 GeV - 183 GeV. Here an analytical power ansatz for the h adronization corrections is compared with hadronization corrections obtaine d by using Monte Carlo generators.