I agree with Randy that a soil test is essential but a few simple tests now will help guide your decision:

- go to your lawn and dig a few holes and take a cup sized sample from each
    - when the soil is neither really dry or really wet take the sample in your hand and make a ball of it.  Does the ball crumble apart when you open your hand ( sandy) or sit like a lump of....clay?
    - get a transparent jar and fill half to two thirds with water. Add a soil sample, shake and let sit overnight.  Do you observe any layers in the soil?  Rich soil will have the heavier clay type particles at the bottom, sand and silt on top with organic matter floating at the very top.

The most likely problem is an absence of organic matter because the developer has given you subsoil to work with. Other possible issues are that there is a heavily compacted layer of soil underneath the soil the developer added.

To get nice looking turf you need sunlight, a good soil profile, water, grass or mixture of grasses adapted to your area and good lawn care practices.  Here are some solutions from previous questions:

- [quickly improve the lawn by removing existing soil, add new, roll and lay sod][1]
- [slowly improve the lawn and outgrow the crabgrass][2]
- [slowly improve the lawn by seeding and better care][3]


  [1]: https://gardening.stackexchange.com/questions/3417/how-do-i-restore-my-lawn-without-having-to-re-sod-the-property/3453#3453
  [2]: https://gardening.stackexchange.com/questions/1390/whats-an-organic-way-to-discourage-crabgrass-from-a-large-lawn/1391#1391
  [3]: https://gardening.stackexchange.com/questions/3688/how-can-we-grow-grass-in-our-heavy-clay-yard/3691#3691