Evidenced by the extensive studies on polyisoprenes with all-cis, all-trans, or mixed cis-trans structures, 1 the regulation of cis-trans configuration of main-chain double bonds offers an important stereochemical handle for adjusting and enhancing properties of polymers with repeating alkene units. 2 Among various approaches towards olefin-containing polymers, olefin metathesis-based polymerization methods, including both ring-opening metathesis polymerization (ROMP) and acyclic diene metathesis (ADMET) polymerization, are ubiquitously practiced due to its broad structural and functional group compatibility. Often, the formation of sterically less congested olefins is thermodynamically preferred, yet, the nature of double bond formation at a metal center renders metathesis polymerization with valuable opportunities to kinetically tune the stereochemistry of the resulting olefin. The selective formation of thermodynamically less favored olefin configurations, such as cis-1,2-disubstituted olefins, could be realized by a series of elegantly developed Mo, W, and Ru catalysts. Therefore, while a classic metathesis polymerization often results in mixed olefin configurations favoring the trans form, cis-enriched polymer backbones are accessible (Scheme 1a). 9 For example, significant progress has been made in cis-selective ROMP, leading to nearly perfect stereochemical control 10 and tailored polymer properties including light-responsiveness and improved shear stability. 11 Further, an ADMET-based approach to cis-polymer backbones has been elegantly demonstrated recently by using a stereoretentive Ru-dithiolate catalyst, which largely broadens the scope of attainable cis-polyalkenamers beyond cis-selective ROMP. While both Scheme 1. Approaches toward cis-enriched polyalkenamers via metathesis polymerization and catalyst requirements for facilitating effective cis-selective ADMET.