Can I be terminated from my position soley on the basis of complaints by others about my work quality?

Colorado is, by default, an "employment at will" state. “Employment at will” is an employment relationship that is not governed by an individual contract of employment, collectively bargained agreement, or statute.  Either party to an employment at-will relationship may terminate the employment for any cause or no cause, except for an illegal reason.  There is no guarantee to either party that employment will continue for any specified duration. As such, unless the complaints were made for some illegal or impermissible purpose, by default, barring an exception listed above, you can be fired for any cause or no cause. An example of where this would not be permissible would be if you were targeted for groundless complaints solely as a pretext to terminate you based on you being a member of a protected class.  Your summary makes no mention of this, so I assume this is not an issue. Please note this response is general in nature and is not legal advice. No attorney client relationship is formed by it.  Furthermore, the response does not represent the opinions or views of LexisNexis or its affiliated companies. I hope this information is helpful. Kind regards,   Cyrus Rajabi