Next to socialization, testing is probably the second most "hot topic" for homeschoolers. Should I or shouldn't I? Do I have to? What am I required to do?
I'm certain most of us realize that not all children test well. There are also students who do better with an "oral" exam as opposed to something on paper. Still others do great with essays, but really suffer when it comes to True/False or multiple choice tests.
Much like anything else in homeschooling, your first step is to decide what works best for your family, and for each student within your family. Your next stop should be your local support group or perhaps the HSLDA web site to find out what your area's homeschool regulations require in the area of testing. Once you have answered both of these questions, you can move on to make decisions about the values of testing, types of testing, and what is available in your area.
A couple of things to consider when deciding whether or not to test your children. Testing sometimes provides an unbiased review for you as the teacher. It helps to point out areas of need and highlights areas where your child excels. I remember one of my kids consistently scored low a couple of years in the area of punctuation and capitalization. I had not seen it during the school year, but the testing showed me an area where we needed a bit of remediation. Seeing areas where your student excels may provide a jumping-off point for extra-curricular activities. Finally, testing may also be good "practice" for your students. If higher education is in your child's future, it's worth having them experience testing while still at home, than to have it be totally unfamiliar when they reach college.
Where to go for testing services? One of the most frequently used options I'm familiar with is the Bob Jones University Testing Service. They primarily provide the Stanford and IOWA tests, and your ability to administer some of their tests will be based on your having a college degree (Bachelors). Seton provides the CAT-E standardized tests for homeschoolers. While I have no experience with these, I know many homeschoolers who use them and are pleased with the results. Their pricing is very reasonable. From the Family Learning Organization you can obtain the California Achievement Tests. Again, I am not personally familiar with this organization, but they are another option.
Whether to test or not is a personal decision ... what is "right" for one family may not be for another. There are many alternatives to testing as well ... probably as many as there are homeschooling families! But we'll leave that to another post.