Background <p>The level of insight finds increasing consideration in the diagnostic of obsessive–compulsive disorder (OCD). Past studies illustrated that low levels of insight are associated with higher symptom severity, worse treatment outcome, and emotion regulation (ER) deficits. However, these results are based on retrospective questionnaires categorizing insight as a trait construct, although the temporal variability of insight has long been established. Therefore, studies using repeated measures designs, i.e., ecological momentary assessment (EMA), are needed.</p> Method <p>Within this EMA study, <i>N</i> = 71 individuals with OCD reported on their symptoms, affect, emotional clarity, ER strategies, perceived ER effectiveness, and insight into symptoms up to six times a day over six days.</p> Results <p>Substantial temporal variations of insight during the assessment period strengthen former evidence that individuals vary in their level of insight over time. Further, higher levels of insight were partly associated with higher perceived ER effectiveness and emotional clarity. Significant associations between symptom occurrence and less insight were consistently found at the momentary level.</p> Conclusions <p>Results show that it might be worthwhile to address insight as a variable state as well as associated constructs (ER, emotional clarity) in the treatment of OCD more explicitly. Replication and extension of our work is needed.</p>