The formation of ice crystals is a widespread environmental process with beneficial effects such as initiating atmospheric precipitation as well as adverse consequences such as biological frost damage. Nature has developed means to either promote or inhibit ice crystal formation, for example ice-nucleating proteins in bacteria or ice-binding antifreeze proteins in polar fish, plants and insects. This presentation will focus on different factors that influence the kinetics of ice crystal formation and growth. Such factors include the catalysis of ice nucleation by biological particles and molecules, and also ice growth inhibition through blocking of ice crystal surfaces by adsorbed antifreeze agents. Mechanistic and molecular aspects of the involved processes will be given special consideration.