This paper presents findings from a one-year longitudinal case study of occupant thermal comfort and related behavioral adaptations in an air-conditioned office building. Long-term data were collected via online daily surveys and datalogger measurements of the local thermal environment and behavior. Behavioral outcomes are examined against both environmental and personal thermal comfort variables. Key personal variables include one's currently acceptable range of thermal sensations, which significantly explains inter-individual variations in thermal comfort responses. Results also show substantial between-day clothing adjustments and elevated metabolic rates upon office arrival, which may affect subsequent thermal comfort and behavior trajectories. Behavior sequencing appears complex, with multiple behaviors sometimes observed within a short time period and certain behaviors subject to contextual constraints. By elucidating the nature of the human-building interaction, the paper's findings may inform the improved measurement, modeling, and anticipation of occupant behavior as part of future sustainable building design and operation practices.