Metathesis step-growth polymerizations in ionic liquids (ILs) was explored to take advantage of the high boiling points of ILs, thereby permitting the use of low pressures at high temperatures. Optimization reactions found that high polymers form efficiently using small amounts of catalyst and short reaction times. For example, high molecular weight main-chain triptycene polymers with high triptycene incorporation were synthesized. This new methodology is applicable to various metathesis reactions that require removal of volatile byproducts as a driving force, including acyclic diene metathesis (ADMET).