Lawn moss is a problem that plagues areas where grass is not happy growing.  There are several conditions that can cause lawn moss to take over:

• low soil fertility
• compaction
• excess moisture
• shade
• acidity
• shallow soil depth
• poor drainage
• drought
• disease

So, while there are commercial products to get rid of lawn moss, it is better to treat the conditions that allowed the moss to establish in the first place.  You will be much more successful at eradicating the moss if you make conditions more favorable for grass.  There are some areas where grass will not grow, and in those areas, moss is not a bad alternative.  It is green and you don't have to mow it.  However, if you have a moss outbreak in an area that gets plenty of sun and could, potentially, be brought back into the lawn, here is how to resuscitate your lawn. Aerate the lawn when conditions are favorable.  Compaction is one of the major factors limiting turf growth.  Aerate and top-dress with compost to increase air circulation and improve drainage in the lawn. Get a soil test so that you can see if the fertility of the lawn could be a factor in encouraging moss growth.  If nitrogen is low, add some fertilizer or compost to the soil.  The soil test will also tell you if the pH of the soil is too low, or acidic.  If this is the case, you can add lime to the soil to raise the pH. Evaluate the sunlight in the area that has moss growth.  If it is very shady, try overseeding with a more shad-tolerant grass type.  If that won't work, you might want to try a shade garden or a groundcover that grows well in shade, instead. Dig into the soil to test its depth. If the soil is less than four to five inches deep, it might not be deep enough to sustain healthy turf.  In that case, if you want to have a lush lawn, you're going to need to add topsoil. Observe the moisture level in the area of the yard with moss.  Too much moisture, or poor drainage, can lead to moss growth.  Most mosses like it wet, and most lawn grasses or turf grasses like a more even, well-drained soil.  If you need to improve drainage in an area, you can try aerating and adding compost.  Compost is like duct tape.  It cures many woes in the soil. Consider pruning overhanging tree limbs. If light is a factor, pruning the canopy above the moss-inflicted area can increase air circulation and let more light into the area, which would make conditions more favorable for grass. Controlling lawn moss is as much a function of lawn maintenance and conditions than anything else.  While you can stop the spread with chemical control, it is better to try to correct the underlying cause of the moss.  Correcting the conditions provides the best long-term solution for controlling lawn moss.