Here are the USDA definitions:

http://www.fsis.usda.gov/factsheets/meat_&_poultry_labeling_terms/index.asp#4

It says the chickens must be "allowed access to the outside." That tells me all the producer needs is an open door somewhere. It says nothing about the chicken's diet.

The Cornucopia Institute has the best egg "scorecard" that I have found thus far...

http://www.cornucopia.org/organic-egg-scorecard/

There's a whole lot of wiggle room in egg labels like free-range and pastured. If they are "free-range", it doesn't mean they are "pastured". If they are "pastured", it doesn't mean the chickens are "free roaming on pasture", which makes them very susceptible to predation btw. I keep a small egg-laying flock. What I've learned is that the more they can naturally forage variety plants and insects, the better nutrition in the egg yolk, and the darker orange in color. So, the egg farmer needs good forage, with plenty of space per bird. Bigger operations have a hard time providing that. If you can, stick with your small local farmer. Discuss soil and forage maintenance with them. Then, taste their eggs and compare with others. You will gain wisdom in how to spend your egg dollars.

The Cornucopia link is good, too.

You definitely want to go beyond "free-range" if you can get them. Free-range is a nice concept if you are for treating the birds more humanely, but what you really want are eggs from birds who get to run around and eat all the cool stuff. I know that all the eggs I find around here for sale, while they might be running around, they are still eating bagged hen chow containing mostly corn. You want the kind that get to eat real bugs, snails, flowers and real greens.

As I understand it regular eggs are from hens caged in tight quarters and not let outside. Free run eggs mean they are allowed to roam in crowded indoor pens, and free range means access to an outdoor area and the ability to scratch around hunting for food like a real chicken. (And real chickens DO eat bugs.)

I used to live near a factory-type egg farm and the hens upper beaks were clipped so they were only able to eat out of dishes. I bought some 'used' hens and had the darndest time chasing them outside at first. They eventually figured it out but still weren't able to eat like normal hens. In the factory farm they were subjected to artificial light making two days out of one so they would lay more eggs more quickly. Prison camp.

For years I have bought local egg farm eggs figuring that at least they were relatively fresh, but this year I switched to genuine certified free range eggs, and there is a world of difference in appearance and flavour. They are worth the extra cost.

Once upon a time, I went to a local (well, mostly local. Let's say driveable..) farm to stock up on some supplies. While pulling into their driveway, I almost ran over a chicken. I didn't. It was fine. That chicken and it's buddies greeted me as I was getting out of my car and then resumed walking around inspecting the landscape... pecking at bugs... just having a grand 'ol time. That's what I want free range to mean. Unfortunately, it doesn't.

I know that farm labels their eggs as pastured.

I checked out the Mother Earth News egg study report. Google it because it talks of all the above, and also, the nutritional qualities of pastured vs caged eggs. The USDA, and perhaps Health Canada too, says that there are no differences in egg quality but the data say otherwise. Very interesting! I sure look at our locally sourced pastured, more expensive eggs differently. As I explained to hubby, even though they are more expensive, the nutrition alone makes them a more affordable food choice....less= more.