The advantages of having a strong professional identity include ethical performances, promoted wellness, and increased awareness of roles and functions among individual counselors (Brott & Myers, 1999; Grimmit & Paisley, 2008; Ponton & Duba, 2009). Scholars in the counseling field have underscored the importance of unified professional identity of counseling, but have yet to create or comprehensively measure the construct. The purpose of this study was to construct a reliable and valid instrument the Professional Identity Scale in Counseling (PISC). The PISC is a 62-item instrument designed to measure professional identity in counseling professionals across all counseling sub-specialties and sub-populations. The PISC's development was based on a comprehensive definition of professional identity derived from the counseling literature. To investigate the factor structure of the PISC, an exploratory factor analysis with the Principle Component Analysis extraction and the varimax rotation method was conducted. The factor analysis produced a meaningful six-factor solution with a total of 54 items. These six factors were Engagement Behaviors, Knowledge of the Profession, Professional Roles and Expertise, Attitude, Philosophy of the Profession, and Professional Values. They approximately accounted for 43.54% of the total variance in a sample of 371 participants. Reliability was supported by internal consistency values as reflected in high Cronbach's coefficient alpha for four factors and acceptable Cronbach's alpha for one factor. Regarding validity, support for convergent validity of the PISC was illustrated as all six subscales significantly correlated with one subscale of the PIVS, Professional Orientation and Values, and five subscales significantly correlated with the other subscale of the PIVS, Professional Development. Social desirability that was measured using the M-C (20) did not appear to impact participants' responses to the instrument items, providing evidence of discriminant validity of the PISC. Additional analysis was conducted to investigate differences among participant groups on the PISC total scores. Results showed significant group differences between master's-level and doctoral-level counseling professionals. Implications for counselors and counselor educators are also discussed related to the findings. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]