When it comes to birth records in Williams Co., OH you have several places to locate them depending on the time period that you are looking for the person. They are the Williams County Records Center, Williams County Health Department and the archives in Bowling Green.
The Records Center is located in the county seat of Bryan, OH. Birth records located here run from 1867 to 1908. This is where you would be able to get certified copies for this time period. As with all places of this type be patient with the staff and allow for some time with your search.
For more recent records you should go to the Williams County Health Department that is also located in Bryan, OH. Here you will find records that run from 1909 to present.
Finally the archives in Bowling Green has the birth records running from 1867-1943. All of these records are on microfilm.
Birth records give you excellent first hand information on time and place of birth. This is also the best source for parentage. Always make copies of these records for proof and verification.
Good luck in your search.