Question: Can an employer exclude certain employees from it's Group Health Insurance policy? 

Answer: Genrally part time employees and contract (1099 paid) employees are excluded from eligibility. the employer can also establish a probationary or waiting period for new employees. This is the length of time the employee would have to work full time before they would become eligible for the health insurance. Typically this period is 90 days, but it can be longer or shorter.
This question from the Yahoo Q&A forum is categorized in the topic: Health