I’m a freelance writer.  I’ve just completed a manual for a business group.  Our agreement is that the group will publish and distribute the manual to its members.  I intend to use the manual in my own workshop.  Can I copyright the work in my own name?

You did no say whose name will appear on the cover or the extent of the rights if any granted to the group.  If you are the acknowledged author on the cover you own the copyright.  If you have not granted any exclusivity to the group, you have all the rights recognized under the Copyright Act.  As you frame your question, commissioned rather than employed by the group the fruit of your labor is not a work for hire as that term is defined in Sec. 101 of the Act.  Make sure that the manual contains a copyright notice in your name.  To be fully covered, application for the copyright should be filed no later than 3 months after publication.