SummaryAn analysis of cine film, to 24 frames per second, of lekking and displaying male Standardwing Birds of ParadiseSemioptera wallaciiprovided the first opportunity to describe displays and posturing detail of this previously little known monotypic genus. A vertical aerial display conspicuously exhibits the previously unremarked upon contrastingly pale primaries in fully plumaged males. This aerial display, whilst unlike any previously described for Paradisaeidae, may be homologous to inverted perch displays byParadisaeaspp. as are other displays of the Standardwing. Male lekking, displays and wing posturing, display perch foliage clearing, vocalisations and female plumage of the Standardwing suggest a much closer affinity toParadisaeaandCicinnurus (Diphyllodes) than previously considered. Views on the position ofSemiopterawithin Paradisaeidae, and behavioural characters shared by species considered closely related to it, are discussed.