My '99 saturn sl won't start. the battery has a charge, and the alternator is good, but it won't turn over.

Hi Vernon, There could be a number of different reasons why your vehicle is failing to start. The battery voltage could be dropping during start and become unable to engage the starter motor to turn the engine. You can check this by trying the key with the head lights switched on. If the lights become very dim, you'll need to check the battery, meaning clean the terminals and then try to start with a jump from another battery. If you achieve start up and it fails again the following morning, you will probably need to replace the battery. There could be a problem with the starter relay or a loose contact for the starter motor, most lik3ely the one connecting to the soliniod. It would be good to know some additional information, such as does a clicking sound come from the starter when engaged? Is there a perceptible drop in voltage output when the starter is engaged? does the enine turn at all? Try what I've suggested and if that does not solve the problem answer the questions and let me know anything else which you may think is relevant. Regards John