IL11 is a pro-inflammatory and pro-fibrotic member of the IL-6 family of cytokines that share commonality in the glycoprotein 130 (gp130) signaling receptor subunit, in combination with their cytokine-specific cognate receptors. This family of cytokines and their cognate receptors have been regarded as important contributors to cancer biology, and may serve as potential biomarkers in disease progression. IL-11 was considered (and is still thought) to be important for platelet function and to be cytoprotective, anti-inflammatory, and antifibrotic in organs, including the lung. However, advances made in the past few years using species-matched IL-11 in disease models in vitro and in vivo have begun to suggest an alternative role for IL-11. IL-11 signaling is now known to be centrally important for lung pathology and promotes a broad range of maladaptive effects, including lung epithelial cell dysfunction, stromal-driven inflammation, and myofibroblast activation.