Attempts to date granites and metamorphics within the Outalpa (Willyaman) Inlier of South Australia were made in order to determine isotopic ages of events within the Proterozoic Olarian Orogeny. Two conformable adamellitic to granodioritic gneisses give a Rb-Sr whole-rock age of 1466 ± 185 Ma, with an initial SR87/Sr86 ratio of 0.7055 ± 0.0507. Petrography, and comparison with age determinations for gneisses elsewhere in the Willyama and Gawler Domains, suggest that this is not the age of gneissosity development, but an updated age conferred during a final phase of the Proterozoic Olarian Orogeny. Micaceous schist, displaying a second deformation phase schistosity (S2), gives an apparent whole-rock age of 1000 ± 197 Ma, with an initial Sr87/Sr86 ratio of 0.8577 ± 0.0692. This age is interpreted to be not equivalent to the time of schistosity development; younger intrusive granites give an older age than the S2 schists. The young age is interpreted to be from updating, but this interpretation cannot be related to any mesoscopic and microscopic texture or structure. Previously dated Crocker Well adamellite and granodiorite give a comparable age: 1076 ± 100 Ma from a ten sample Rb-Sr isochron. Porphyritic granites were intruded during and after the final phase (D3) of the Olarian Orogeny. These give a Model 2 isochron whole-rock age of 1503 ± 233 Ma, with an initial ratio of 0.7157 ± 0.1440, which is indistinguishable from the two suites of D1 gneisses. Widespread partial recrystallisation and Sr-isotopic transfer probably occurred throughout the Outalpa Block at this time. Selected areas of the Olary subdomain underwent Sr-isotopic homogenisation during the Ordovician Delamerian Orogeny. Lithologies which give ages corresponding to the Delamerian Orogeny exhibit extensively sericitised feldspars.