Reductions in wheat plant height are associated with genotypic increases in harvest index and grain yields. The largest single increase in yield was seen in development of semi-dwarf wheats with the gibberellic acid (GA)-insensitive, Rht1 (syn. Rht-B1b) and Rht2 (syn. Rht-D1b) dwarfing alleles. A suite of GA-responsive dwarfing genes are also available and their neutral effects on seedling vigour suggest their potential in being deployed singly, or in combination with GA-insensitive dwarfing genes to reduce plant height. A set of BC4 to BC5 Near-Isogenic Lines (NILs) were developed in the tall, spring wheat variety Halberd to compare performance across GA-sensitive (Rht5, Rht8, Rht12, Rht13, Rht18) and insensitive (Rht1, Rht2, Rht3, R10) dwarfing genes singly or in doubled-dwarf combinations. In irrigated and rainfed field experiments in multiple years and sites across Australia, height reduction in the Halberd Rht1 and Rht2 Near-Isogenic Lines (NILs) was consistent with reductions in the CIMMYT Rht1 and Rht2 NILs(12-16%). The smallest height reduction was in Rht13 NILs (c. 9%), largest in Rht3,Rht10 and Rht12 (51, 56 and 50%, respectively), and intermediate for Rht5, Rht8 and Rht18 (12, 13, and 18%, respectively). The doubled-dwarfs were always shorter than either single-dwarf parents with the greatest height reduction in Rht1i-2 doubled dwarfs(-39%). Height reduction in other doubled-dwarfs varied from - 21% (Rht1i-13) to -32% (Rht2i-18). Genotypic reductions in height were genetically correlated with increases in harvest index, grain number and yield. We also report on the influence of the different dwarfing genes on above- and below-ground (root) biomass, tiller and spike growth, and grain quality from across multiple field experiments.