So much has been written about developing mission statement, it's time to make some sense of it all.
Mission or purpose should be enduring -- something the pursuit of which is limitless.
A company's mission explains why the organization exists - and what its purpose is. (Not what you hope it is, or want it to be - but what your organization is.)
The mission must be long-term. The purpose should be valid 20-30 years or more - regardless of changes in technology, economics, or customer trends.
Your organization's mission should focus on why - not how. "How" is strategy, and will change over time.
For examples of mission statements, see Man on a Mission.
For a humorous look at mission statements, see Dilbert's Mission Statement Generator.
BOTTOMLINE: The mission of Six Disciplines? "To help the best small businesses to achieve lasting excellence."