In the field of indoor overheating analysis, the development of valid indicators and thresholds is recognized as crucial for assessing overheating risk or heat resilience in rooms and buildings. This assessment process is typically undertaken through methods such as building performance simulation or indoor monitoring. This chapter focuses on exploring the existing criteria and thresholds derived from a variety of standards and methodologies, which are pertinent to the assessment of overheating in free-running buildings. The goal is to establish a refined set of indicators for the assessment of residential buildings, integrating the strengths of existing methodologies. In the proposed indicator set, several key elements are integrated: temperature exceedance hours, weighted for their significance (as informed by ASHRAE 55 and DIN 4108-2), adaptive temperature thresholds that reflect the adaptive nature of human thermal sensation (based on EN 16798-1 and ASHRAE 55), and a criterion for night-time indoor temperatures (sourced from CIBSE TM52 and TM59). The variability in room usage, as outlined in CIBSE TM59, is also considered and extended. The effectiveness of this indicator set was evaluated through simulations of an apartment building in various summer regions of Germany. These results were then compared with the outcomes derived from existing overheating assessment standards, specifically CIBSE TM59, CIBSE Guide A, and DIN 4108-2. The chapter concludes by discussing the complexities involved in formulating more valid and reliable thresholds for overheating assessment. Future enhancements in this area should include the integration of insights from public health literature and the consideration of indicators considering humid heat sensation.