The short form of the Bielefeld Partnership Expectations Questionnaire (BPEQ12) measures three partner-related attachment scales: fear of rejection, readiness for self-disclosure and conscious need for care. In addition to factor structure and reliability, the present study examined measurement invariance and validity using a non-clinical and a clinical sample of college students (N=208). Besides the BFPE12, the following Questionnaires were assessed: Short Form of Experiences in Close Relationships - Revised (ECR-RD8), Outcome Questionnaire (OQ-30), revised Beck Depression Inventory (BDI-II), Social Phobia Inventory (SPIN), and Test Anxiety Inventory (TAI-G). The factor structure is tested using confirmatory factor analysis (CFA), the internal consistency of the scales is quantified using McDonald's ω, the measurement invariance is investigated with two-group structural equation models, and the validity is examined using correlation and regression analyses. In both samples, the factor structure was confirmed (CFI>0.93; TLI>0.93; RMSEA<0.08; SRMR<0.08) and the reliability of all three scales was acceptable (ω>.7) - with the exception of need for care in the non-clinical group. We found configurational, metric and scalar measurement invariance regarding to the assignment in the clinical and non-clinical sample. In terms of convergent validity, fear of rejection and conscious need for care were associated with attachment-related anxiety (r=0.771 and r=0.539, p<0.001) and low readiness for self-disclosure was correlated with attachment-related avoidance (measured with ECR-RD8, r=- 0.704, p<0.001). Overall, the present study supports the factor structure, measurement invariance, reliability, and validity of the BPEQ12 in clinical and non-clinical samples.