The measurement of self-efficacy among trainee counsellors and psychologists provides a way of determining the degree of confidence these emerging professionals have in their ability to meet the requirements for practice. Recent research has shown that the newly developed Psychology and Counselling Self-Efficacy Scale (PCES) is an effective tool for evaluating multiple dimensions of this construct, namely Research, Ethics, Legal Matters, Assessment & measurement, and Intervention. The aim of this preliminary study was to ascertain the discriminant validity of the PCES by exploring pilot data responses to a range of wellbeing, personality, and self-efficacy scales. This study provides a necessary and logical next step in the development of the PCES by identifying how well the scale relates to, and discriminates against, a number of theoretically relevant factors. Participants were 67 (M age=33.80, SD age=10.30) trainees (50 females and 17 males) completing postgraduate degrees in counselling or psychology at a large university in Melbourne, Australia. Demographic information and a variety of measures in addition to the PCES were completed, including wellbeing scales (DASS-21; SWEMWBS; LOT-R; CD-RISC-10; SWLS), a brief measure of personality (TIPI), and a measure of career decision self-efficacy (CDSE). Preliminary analyses indicated that each PCES subscale was normally distributed and showed acceptable internal consistency. Correlation analyses indicated that for the overall sample, few significant relationships existed between the PCES subscales and personality dimensions. Significant positive relationships were found between the PCES subscales and resilience, life-satisfaction, SWEMWBS, and CDSE dimensions, although these correlations were weak. A different pattern of relationships emerged when these scales were analysed separately by gender, including interesting relationships with personality factors and divergent relationships with optimism. The relationships between the PCES subscales and psychological wellbeing might indicate that psychology and counselling students who are more confident in their ability to meet the demands of their future career report a greater sense of wellbeing. The relationships between the PCES and the CDSE show that the new scale is related to career-decision self-efficacy, but measuring a different construct. Gender differences noted in the relationship between the PCES and other measures suggest that self-efficacy may relate to different outcomes for males and females. Although a cross-sectional correlational design, the study provides further support regarding the validity of the PCES, and potential for it to predict a variety of other constructs relevant for professional practice.