Preheat oven to 350°F.
In a small bowl, mix together flour, baking soda, and salt. Set aside.
In a large mixing bowl, mix the butter and brown sugar on medium speed until smooth and creamy. Reduce the mixer speed to low and beat in the eggs one at a time mix until well blended. Mix in the vanilla.
Add the dry ingredients and mix just until blended. Stir in the oats and chocolate chips. Cover and refrigerate dough for 30 minutes.
Using two spoons or a small cookie scoop, drop by rounded spoonfuls on to cookie sheets. Bake 12 to 14 minutes, until edges are set but the center is still soft.
Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.
If your dough isn't chilled, your baked time will be reduced to 10 to 12 minutes.