Most companies give a performance review at least once a year that clarifies what an employee is doing well, and what needs to be improved. While it can be difficult to tell a worker that his performance isn't up to par, choosing your words carefully can help change problematic behavior without building resentment.
Ask the employee if he was aware of the problem behavior. Listen to his response without interrupting. If the behavior is new, and the employee was previously meeting expectations, ask for any reasons for the change in performance.
Suggest examples of alternative behaviors, and brainstorm with the employee for different ways of handling the same situation. Tell the employee what level of performance would be acceptable, and ask him to give an action plan for how he will meet these expectations.
Confirm with the employee that he understands the requirements of the position, the time frame for a reevaluation of his performance and that he is committed to making the necessary changes.
Do not give criticism without providing advice as to how to improve the behavior. This will be seen as an attack. Don't begin the meeting with a completely different subject, and then switch to the topic of the negative review. Focusing on the problem will help make the point of the conversation clear. However, if the employee is performing some parts of his job well, mention them. This shows you are capable of recognizing positive behavior.
Do not make critical statements about his personality, such as, "You don't care about the rules!" State the specific behavior that is of concern, along with examples showing when the employee has demonstrated this behavior. For example, "Our rules say you must always wear a helmet on the job site. You were observed without a helmet on three occasions this month. What happened?"
If the employee disagrees with the negative evaluation, don't get into an argument. If she brings up a point that hadn't occurred to you, ask for some time to think about it. Otherwise respond by saying something such as, "I see how you feel, but for now, I need to insist that you follow this policy in the future."
Don't discuss the behavior or opinions of other employees. An evaluation should be an objective measure of this employee's performance against the requirements of the job. Additionally, if other employees are also having performance issues, this doesn't excuse the behavior of the worker being evaluated.