The Okenyenya igneous complex, of Mesozoic age and located in northwestern Namibia, is notable for its extremely wide range of rock types of both tholeiitic and alkaline affinities. The intrusive rocks, which range from highly alkaline, silica-poor lamprophyres through to quartz-syenite, have been emplaced by a variety of contrasting mechanisms. A detailed geological map of the igneous complex is presented, together with a structural reinterpretation of a number of the component intrusions. A model of emplacement is proposed comprising: Stage 1, emplacement of a tholeiitic gabbro-quartz monzodiorite sill or cone sheet complex, followed by Stage 2, the intrusion of picritic gabbro dykes; and Stage 3, the emplacement of alkaline gabbros into high level magma chambers. Stage 4 involved the injection of syenite and quartz syenite as a series of dykes and sills, primarily in the southwest of the complex but including a major peripheral ring dyke. Stage 5 saw the emplacement of concentric intrusions of nepheline syenite and essexite during the last major phase of magmatism, with the final magmatism of Stage 6, involving the emplacement of lamprophyric rock types as narrow dykes, small stocks and volcanic diatremes. The identification of a major peripheral ring fault is fundamental to a new model proposed for the evolution of the intrusive complex. The ring fault is interpreted as having formed during cauldron collapse of an overlying major volcano coincident with voluminous syenitic magmatism. The probability that significant vertical displacement has occurred along the fault poses difficulties in adjudging the exact nature and former extent of early gabbroic intrusions. Stresses, resulting from unequal displacement on different segments of the encircling fault, impacting on the structurally heterogeneous gabbroic rocks are believed to have significantly determined the geometry and distribution of the younger intrusions within the complex.