Native Contacts Won't Sync With Exchange Server

I have an Exchange Internet Account set up on a Macbook Pro. Native Mail, Calendars, Reminders, and Notes all seem to synchronize properly (although Calendars can be sporadically flaky) with the Exchange Server. However, for some reason, new entries in the native Contacts app are not syncing with the Exchange Server and are, therefore, not available to other devices (iPad, iPhone) that are also set up with the identical account information.