INTRODUCTION: In internet-based mental health research, the efficacy of assessment tools is pivotal. Extensive questionnaires often deter participant completion, undermining data integrity. This presentation focuses on the application of brief yet effective measures: The PHQ-2 and GAD-2 as ultra-brief measures for psychopathology, and Brunnsviken brief quality of life inventory (BBQ) and Questionnaire on Well-Being (QWB) as positively valanced measures for positive functioning. By prioritizing instruments with concise formats and positive framing, such as the BBQ and QWB, our research aims to enhance response rates and data quality. We explore psychometric findings from various internet-based trials, demonstrating the utility of these measures in capturing in-treatment fluctuations and informing treatment outcomes. METHOD: We outline findings from three studies at different stages of development. Primary statistics are obtained from ROC curve and factor analyses. RESULTS: Preliminary results suggest that brief measures like the PHQ-2 and GAD-2 can monitor in-treatment fluctuations in symptoms as effectively as their full-scale equivalents. The BBQ, indicating positive functioning, can validly assess divergent subgroups (e.g., vulnerable persons). Notably, BBQ total scores below 39 are linked with significant psychopathology. Preliminary results for the QWB indicate total scores are negatively associated with psychopathology and positively correlated with positive affect. CONCLUSIONS: Ultra-brief measures of psychopathology are too often used incorrectly; usage is recommended to be bound to in-treatment monitoring of treatment outcomes. Collecting data more frequently through concise surveys can provide insights into the mechanisms driving change. Treatment trials often overlook positive functioning. Thus, we encourage using the BBQ and QWB as they are psychometrically valid, freely available, and inform treatment outcomes beyond standard measures of psychopathology.