The Borderline Symptom List – Short Version (BSL-23) is a 23-item self-rating instrument for specific assessment of borderline personality disorder (BPD) symptomatology in adults (18+). The scale assesses DSM BPD diagnostic criteria (e.g., affective instability, recurrent suicidal behaviour, gestures, or threats, or self-mutilating behaviour, and transient dissociative symptoms) in addition to items that are based on borderline-typical empirical findings regarding self-criticism, problems with trust, emotional vulnerability, and proneness to shame, self-disgust, loneliness, and helplessness (Kleindienst et al., 2020).
Developed by Bohus and colleagues (2009) at the Central Institute of Mental Health in Mannheim, Germany, the BSL-23 was derived from the original 95-item Borderline Symptom List to provide a more practical assessment tool that preserves comprehensive coverage of BPD symptoms while minimising respondent burden.
The theoretical foundation of the BSL-23 draws from multiple sources: DSM diagnostic criteria, the revised version of the Diagnostic Interview for Borderline Personality Disorder (Zanarini et al., 1989), and the clinical experiences of both experts and individuals with BPD. Items were selected from the BSL-95 based on their sensitivity to change and ability to discriminate BPD patients from other clinical groups. The scale assesses core DSM BPD diagnostic criteria including affective instability, recurrent suicidal behaviour, self-mutilating behaviour, and transient dissociative symptoms. In addition, items capture borderline-typical empirical findings regarding self-criticism, problems with trust, emotional vulnerability, and proneness to shame, self-disgust, loneliness, and helplessness (Kleindienst et al., 2020).
The BSL-23 uses a one-week reference period, asking respondents to rate how much each statement applied to them during the past week on a 5-point scale from 0 (not at all) to 4 (very strong). An additional wellbeing item (Item 24) asks clients to rate their overall wellbeing from 0 to 100, which is reported separately from the total score. This item correlates strongly with specific indicators of wellbeing for individuals with BPD, including self-perception, affect regulation, dysphoria, loneliness, and hostility (Bohus et al., 2007).
The BSL-23 is commonly used in mental health settings to assess the severity of BPD symptomatology and monitor treatment progress. It is particularly useful in Dialectical Behaviour Therapy (DBT) programs, where it serves as a treatment monitoring tool to track symptom change over time. Unlike screening instruments designed solely to detect the presence of BPD, the BSL-23 was optimised to reflect levels and changes in severity of BPD symptomatology, making it well-suited for repeated administration throughout treatment. The scale’s brevity, typically requiring approximately four minutes to complete, minimises respondent burden and allows for frequent administration without significant disruption to clinical sessions.
Individuals with high scores on the BSL-23 are more likely to have BPD and associated challenges with managing emotions, self-image, relationship issues, and general functioning in everyday life. The scale can inform treatment planning by identifying current symptom severity, tracking response to intervention, and providing empirical feedback to clients about their progress.
The average score of items (range 0 to 4) is calculated, with a higher score indicating greater impairment. The total average score is computed by summing responses to all 23 items and dividing by 23. Scores can be calculated for respondents who complete at least 21 of the 23 items.
Six grades of symptom severity were defined by Kleindienst et al. (2020) based upon the distribution of scores in a large calibration sample of individuals with BPD (n = 241). The severity categories are based on standard deviation units from the mean score of the calibration sample:
Scores of 1.50 or higher indicate responses consistent with BPD, with empirical data showing this cut-off score discriminates between BPD patients and individuals with other clinical psychopathology. A lower threshold of 0.64 provides optimal discrimination between individuals with BPD and healthy controls.
Three percentile comparisons are provided, comparing the respondent’s score to: (1) a healthy control group (n = 356; no history of psychopathology), (2) a clinical control group (n = 176; individuals with Axis I disorders but no BPD diagnosis), and (3) a BPD group (n = 317; met DSM-5 diagnostic criteria for BPD) from Kleindienst et al. (2020). A percentile of 50 means the client has scored at the typical level compared with the comparative group.
An average score of 1.50 corresponds to a percentile of 17 compared to the BPD group and a percentile above 99 compared to the healthy control group, indicating this score is typical for someone with BPD but extreme compared to someone without a psychiatric diagnosis.
There is an additional question (Item 24) that provides an indication of the client’s perspective on their overall wellbeing, but it is not included in the overall score. The rating on this last question (from 0 to 100) is strongly correlated with specific indicators of wellbeing for BPD patients, including self-perception, affect regulation, self-destruction, dysphoria, loneliness, intrusions, and hostility (Bohus et al., 2007).
On first administration, a bar graph displays the total average score with severity range bands for reference.
A comparison graph is also presented showing the respondent’s score relative to the BPD diagnosed group, the clinical control group, and those without any psychiatric diagnosis.
On multiple administrations, a line graph tracks the total average score over time to visualise changes in symptom severity.
The BSL-23 demonstrates strong construct validity as a measure of BPD-specific symptomatology. Convergent validity is supported by high correlations with depression as measured by the Beck Depression Inventory (r = .87) and general severity of psychopathology as measured by the SCL-90-R Global Severity Index (r = .89; Bohus et al., 2009). In validation samples, BSL-23 severity grades showed large correlations with GSI scores (ρ = .77) and large correlations with the number of DSM BPD criteria (ρ = .80; Kleindienst et al., 2020).
Discriminant validity is demonstrated by the scale’s excellent ability to distinguish BPD patients from healthy controls (ROC AUC = .997) and from individuals with other psychiatric conditions such as anxiety disorders, major depression, and schizophrenia (ROC AUC = .85; Kleindienst et al., 2020). A BSL-23 score of 1.50 provides optimal discrimination between individuals with BPD and those with other clinical psychopathology, while a lower threshold of 0.64 provides optimal discrimination between individuals with BPD and healthy controls.
The BSL-23 demonstrates excellent internal consistency, with Cronbach’s α = .97 in the original validation study (Bohus et al., 2009). Test-retest reliability is adequate (r = .82) within a one-week interval. These psychometric properties have been replicated across multiple international validation studies, including French (α = .94; Nicastro et al., 2016), Spanish (Soler et al., 2013), and Chinese versions (Yang et al., 2018; Shen et al., 2023). The scale has translations available in over 18 languages (Kleindienst et al., 2020).
The BSL-23 has a single-factor structure with one highly dominant eigenvalue, reflecting the unidimensional nature of BPD symptom severity (Bohus et al., 2009). This single-factor structure has been consistently replicated across international validation studies and supports the use of a total score for clinical interpretation.
The BSL-23 is sensitive to therapeutic change, showing meaningful reductions following evidence-based treatments including DBT (Bohus et al., 2009; Nicastro et al., 2016; Robinson et al., 2018). A Reliable Change Index (RCI) was calculated using the Jacobson-Truax method, based on the internal consistency of α = .97 (Bohus et al., 2009) and the standard deviation of 0.86 from the treatment-seeking BPD sample (Kleindienst et al., 2020). A change of 0.41 average score points or more represents statistically reliable change at a 95% confidence level.
Kleindienst et al. (2020) established normative data from a large multi-sample study (N = 1,090) to develop and validate a severity classification system for the BSL-23. Three independent samples are used to provide context for interpreting individual scores:
BPD involves a range of symptoms that affect emotions, relationships, self-image, and behaviour. Common experiences include intense and rapidly shifting emotions, chronic feelings of emptiness, difficulty controlling anger, unstable relationships that alternate between idealisation and devaluation, a persistent fear of abandonment, and an unclear or shifting sense of identity. Some individuals engage in impulsive behaviours such as reckless spending, substance use, or unsafe sexual behaviour. Transient paranoia or dissociative symptoms (feeling detached from oneself or reality) may emerge during periods of stress. Not everyone with BPD experiences all of these symptoms, and severity varies considerably between individuals.
BPD and bipolar disorder are distinct conditions with different symptom patterns and treatment approaches. Bipolar disorder involves episodes of mania or hypomania (elevated mood, increased energy, reduced need for sleep) alternating with episodes of depression, with each episode typically lasting days to weeks or longer. In BPD, mood shifts tend to be more rapid (often occurring within hours) and are frequently triggered by interpersonal events such as perceived rejection or conflict. The emotional instability in BPD is also accompanied by other features not central to bipolar disorder, including identity disturbance, chronic emptiness, fear of abandonment, and patterns of unstable relationships. It is possible to have both conditions simultaneously, and accurate diagnosis is important because the treatments differ.
The BSL-23 uses a one-week reference period, making it suitable for frequent administration without concerns about overlapping timeframes. In intensive treatment settings such as DBT programs, the scale is often administered weekly or fortnightly to closely track symptom fluctuations and treatment response. In standard outpatient settings, monthly or session-by-session administration may be more practical. The scale’s brevity (approximately 4 minutes to complete) minimises respondent burden, allowing for repeated use without significant disruption to clinical sessions. Regular administration enables clinicians to identify patterns over time, detect early warning signs of deterioration, and demonstrate progress to clients, which can itself be therapeutically beneficial for individuals who struggle to recognise their own improvement.
Item 24 asks clients to rate their overall wellbeing on a scale from 0 to 100 and is separate from the BSL-23 total score. This single-item measure provides a global snapshot of how the client perceives their current functioning and quality of life. Research has shown that responses to this item correlate strongly with specific indicators of wellbeing in individuals with BPD, including self-perception, affect regulation, dysphoria, loneliness, and hostility. Clinically, this item offers a quick subjective check-in that can be compared against the more detailed symptom profile provided by the BSL-23 total score. Discrepancies between the wellbeing rating and symptom severity may warrant further exploration, for instance, a client reporting high symptom severity but relatively preserved wellbeing, or vice versa.
Bohus, M., Kleindienst, N., Limberger, M. F., Stieglitz, R.-D., Domsalla, M., Chapman, A. L., Steil, R., Philipsen, A., & Wolf, M. (2009). The short version of the Borderline Symptom List (BSL-23): development and initial data on psychometric properties. Psychopathology, 42(1), 32–39. https://doi.org/10.1159/000173701
Bohus, M., Limberger, M. F., Frank, U., Chapman, A. L., Kühler, T., & Stieglitz, R.-D. (2007). Psychometric properties of the Borderline Symptom List (BSL). Psychopathology, 40(2), 126–132. https://doi.org/10.1159/000098493
Bohus, M., Kleindienst, N., Limberger, M. F., Stieglitz, R.-D., Domsalla, M., Chapman, A. L., Steil, R., Philipsen, A., & Wolf, M. (2009). The short version of the Borderline Symptom List (BSL-23): Development and initial data on psychometric properties. Psychopathology, 42(1), 32–39. https://doi.org/10.1159/000173701
Kleindienst, N., Jungkunz, M., & Bohus, M. (2020). A proposed severity classification of borderline symptoms using the borderline symptom list (BSL-23). Borderline Personality Disorder and Emotion Dysregulation, 7, 11. https://doi.org/10.1186/s40479-020-00126-6
Nicastro, R., Prada, P., Kung, A. L., Salamin, V., Dayer, A., Aubry, J. M., Guenot, F., & Perroud, N. (2016). Psychometric properties of the French borderline symptom list, short form (BSL-23). Borderline Personality Disorder and Emotion Dysregulation, 3(1), 4. https://doi.org/10.1186/s40479-016-0038-0
Robinson, S., Lang, J. E., Hernandez, A. M., Holz, T., Cameron, M., & Brannon, B. (2018). Outcomes of dialectical behavior therapy administered by an interdisciplinary team. Archives of Psychiatric Nursing, 32(4), 512–516. https://doi.org/10.1016/j.apnu.2018.02.009
Shen, J. E., Huang, Y. H., Huang, H. C., Chen, Y. L., Yen, C. F., & Ko, C. H. (2023). Psychometric properties of the Chinese Mandarin version of the Borderline Symptom List, short form (BSL-23) in suicidal adolescents. Borderline Personality Disorder and Emotion Dysregulation, 10, 23. https://doi.org/10.1186/s40479-023-00230-3
Soler, J., Vega, D., Feliu-Soler, A., Trujols, J., Soto, Á., Elices, M., Ortiz, C., Pérez, V., Bohus, M., & Pascual, J. C. (2013). Validation of the Spanish version of the borderline symptom list, short form (BSL-23). BMC Psychiatry, 13, 139. https://doi.org/10.1186/1471-244X-13-139
Yang, H., Lei, X., Zhong, M., Zhou, Q., Ling, Y., Jungkunz, M., & Yi, J. (2018). Psychometric properties of the Chinese version of the brief borderline symptom list in undergraduate students and clinical patients. Frontiers in Psychology, 9, 605. https://doi.org/10.3389/fpsyg.2018.00605
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