One central principle for a successful assessment center is that all members of the assessment process must work as a team. The assessors first should become familiar with the targeted department or unit by meeting with all individuals involved in the assessment process, reviewing and updating job descriptions, conducting a job analysis, meeting with candidates to help them understand the assessment process, developing procedures to evaluate the candidates. Assessment centers can use a number of different types of exercises to evaluate candidates and observe how they would react in certain situations. The team should also interview each candidate. Assessment teams should include a police psychologist to take part in assessment activities as well. The next step is to have two or three assessors evaluate the candidates, reach a consensus on each score, and rank the candidates by converting the values into percentage ratings. Assessors should also develop a narrative report about the candidates. They should provide candidates an opportunity to talk to the assessors and receive feedback after the team makes the promotion selections. Following these principles will make the assessment an effective selection tool, will help the agency develop a standard, and will have a residual effect for all the candidates who participate. Notes and photographs of the authors