R eceptor-mediated airway smooth muscle (ASM) contraction via G_αq, and relaxation via G_αs, underlie the bronchospastic features of asthma and its treatment. Asthma models show increased ASM G_αi expression, considered the basis for the proasthmatic phenotypes of enhanced bronchial hyperreactivity to contraction mediated by M₃-muscarinic receptors and diminished relaxation mediated by β₂-adrenergic receptors (β₂ARs). A causal effect between G_i expression and phenotype has not been established, nor have mechanisms whereby G_i modulates G_q/G_s signaling. To delineate isolated effects of altered G_i, transgenic mice were generated overexpressing G_αi2 or a G_αi2 peptide inhibitor in ASM. Unexpectedly, G_αi2 overexpression decreased contractility to methacholine, while G_αi2 inhibition enhanced contraction. These opposite phenotypes resulted from different crosstalk loci within the G_q signaling network: decreased phospholipase C and increased PKCα, respectively. G_αi2 overexpression decreased β₂AR-mediated airway relaxation, while G_αi2 inhibition increased this response, consistent with physiologically relevant coupling of this receptor to both G_s and G_i. IL-13 transgenic mice (a model of asthma), which developed increased ASM G_αi, displayed marked increases in airway hyperresponsiveness when G_αi function was inhibited. Increased G_αi in asthma is therefore a double-edged sword: a compensatory event mitigating against bronchial hyperreactivity, but a mechanism that evokes β-agonist resistance. By selective intervention within these multipronged signaling modules, advantageous G_s/G_q activities could provide new asthma therapies.