In May of 2005, I had a problem...the good kind of problem. Two organizations wanted to hire me to begin working that July. I obviously couldn't work for the both of them so I had a big decision to make. Declining a job offer intelligently takes foresight, planning, and professional acumen. Follow these steps to accept the right position and decline the other intelligently:
1. Ensure the decision is right for you: Look at both job offers objectively as they compare to your values. Are you being compensated the way that you believe? Will you have the autonomy that you crave? How does the position fit in with your long-term career plans? Will your potential supervisor be one that you feel you can learn from? These and other questions need to be considered in light of what is important to you. Search you soul, make a pro/con chart, and consult with mentors if you need to to make the right decision.
2. Accept the job offer and get it in writing: This is a crucial step to declining a job intelligently, as it will give you the security you need to confidently turn down the other job. Getting a job offer in writing doesn't guarantee the job in event that funding is cut or some other abnormal circumstance occurs (unless you have a contract), but it will give you the good-faith security you need to turn down the other offer.
3. Contact the other job and be direct about your decision: When you contact the organization that you are turning down, be direct and to-the-point with them...but not too direct. For example, if you get the feeling that your future supervisor will be a slave-driving micromanager, it would be considered rude to tell him/her that, or even to tell the organization's recruiter that. Think of the broad, general reasons why the job isn't the right one for you, including your career goals, work responsibilities, and type of work.
4. Expect questions (and possibly a counter-offer): Be prepared for any questions that may come your way, even direct questions like "are you declining the job because you think that your future supervisor will be a slave-driving micromanager?" Tactful but brief responses are required here: emphasize that you have given the positions a lot of thought and you feel that the other one is right for your career, goals, and the time in your life (if these apply). If salary was the deciding factor for you and they try to lure you with a higher salary, you can stick to your original plan and turn them down or you can reconsider. Just be aware of the impact of making a decision like this on your professional persona.
5. Say thank you: As always, thank the organization for the opportunity and the interest. Your graciousness here can open opportunities in the future.
While you may be initially excited to have to entertain two job offers, you still need to show the utmost professionalism and consideration when choosing one over the other and when accepting one and turning the other down.