Grass can be composted, but a lot added to your home compost bin can cause problems. Make sure you add about the same volume of dry material (such as shredded paper, scrunched up cardboard or dry leaves) with the grass.
Special grass-cycling mowers chop up the grass into extra fine particles which are quickly broken down and absorbed back into the lawn. Available from most large garden centres and by mail order. See Mail Order Catalogues.
Grass is accepted for large scale composting via the garden waste collections. See Garden Waste.