Work with your library's governing body to form a small committee to review and write the policy. The Idaho Commission for Libraries suggests that the governing body appoint a member to work with the director and another staff member to write the policy. Including a library staffer is important, as the staff is most in tune to the needs of the library community. Using a committee to draft the policy safeguards against one individual's prejudices influencing the policy. If the policy is being written for specific subject, however, the subject librarian may be your best resource for drafting the policy.
Gather information. Review your library's long-range plan and current collection development policy. If there is no written policy, write down how your library currently selects materials --- and how that process supports the library's mission. Clarify whether the collection will be designed to meet the needs of the average user or the expert. Discuss whether the library will primarily add print materials or non-print materials. Determine if the library's focus is acquiring older materials to complete its collection or seeking out newer materials. Specify whether your library will acquire primarily English materials or materials in other languages. Note the library's stance on special collections or purchasing multiple copies of popular items.
Discuss potential changes in light of your current policy and long-range goals. If certain materials have become obsolete, consider discontinuing their future purchase. If your community is asking for a new format or new sorts of materials, write your policy to support these demands.
Write the policy. Make sure to include information that the American Library Association explicitly identifies as important to a good policy. This information includes: introduction to the policy statement, general purpose, brief note about the library, general subject boundaries, languages, geographical areas, types of materials collected, format of materials collected, special collections and manuscripts, other resources available, detailed subject areas and weeding and deselection. You may also look to other libraries' policies for inspiration.
Present the policy to your governing body for approval. The Idaho Commission for Libraries suggests presenting the policy at one meeting, then reconvening at a later date to vote on its approval. This gives those involved in the approval process time to review the materials and make suggested edits. Request that these edits/comments be forwarded to the writing committee --- before the approval meeting --- so that they may be incorporated into the policy.
Review and update the policy yearly. The policy will only remain useful if it is kept relevant. Revisiting the policy on an annual basis also provides the opportunity to remind the governing body and library staff about their responsibilities in implementing the policy.