Laying hens produce a large number of eggs on an annual basis. In recent years, permitted housing methods in the EU have changed to enriched cages and cage-free systems (i.e. barn, free-range and organic production methods), but worldwide hens are still also housed in conventional cages. The various characteristics of these systems are discussed. Different systems have various pros and cons with regards to bird welfare. Conventionally-caged hens have weaker bones and lack behavioural freedom, whereas hens from enriched cages benefit from some improvements such as nest boxes, perches, greater space, and litter for pecking and scratching. Cage-free hens have the most behavioural freedom and better bone strength, but they are also at risk of greater keel bone damage (particularly with multi-tier structures), exposure to pathogens (particularly with free-range and organic), and greater mortality. Improvements to reduce keel bone damage in particular are considered.