Defining competence in colonoscopy is elusive because there is no objective means by which to assess skills.

We describe the development and validation of the Mayo Colonoscopy Skills Assessment Tool (MCSAT) designed for the assessment of cognitive and motor skills during colonoscopy training.

Prospective development and analysis of the validity evidence of a unique colonoscopy skills assessment tool.

Outpatient endoscopy center, Mayo Clinic in Rochester, Minn, from July 2007 through May 2010.

All gastroenterology fellows in training at this institution during the study period.

The MCSAT was developed and used to assess fellow performance over a 3-year period.

A descriptive report of the form's development, correlation of each MCSAT assessment parameter with overall competency scores, and a comparison of MCSAT scores at various stages of training.

There is strong individual item correlation to overall skills assessment for many of the parameters as well as significant improvement in all parameter scoring at increasing stages of experience.

Compliance with MCSAT completion was 62% of all colonoscopies performed.

The MCSAT provides a valid means to objectively assess individual cognitive and motor skills in a continuous manner throughout colonoscopy training. The resultant data can eventually be used to establish average learning curves in colonoscopic skills and define competency thresholds based on performance scores rather than basing assessment simply on numbers of procedures performed.