Cyclodextrins (CDs) were found to initiate polymerization of lactone to give polyesters with a CD ring at the end of the polymer chain in high yields only by mixing and heating with monomer without cocatalysts or solvents. CD-tethered polyester propagates with the formation of poly-pseudorotaxane, which is necessary to initiate further polymerization. CDs threaded onto the polymer chain are also essential for maintaining the propagating state of the polyester. By polymerizing with CD, switching the activity of the polymerization by photoisomerization was demonstrated. This polymerization system showed specific substrate recognition, releasing the products from the active site. By using the above polymerization system, beta-CD nanospheres which initiates the oligomerization of lactone were constructed. It was found that the formation of poly-pseudorotaxane on the nanosphere enabled further polymerization activity for lactone. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4469-4481, 2009