Repository containing datasets obtained for Levy et al. 2023, available online here: https://doi.org/10.1016/j.cub.2023.02.035 Github link to related analysis code: https://github.com/dattalab/spontaneous-behavior-reflects-individuality-not-estrous Abstract Behavior is shaped by both the internal state of an animal and its individual behavioral biases. Rhythmic variation in gonadal hormones during the estrous cycle is a defining feature of female internal state, one that regulates many aspects of sociosexual behavior. However, it remains unclear whether estrous state influences spontaneous behavior, and if so how these effects might relate to individual behavioral variation. Here we address this question by longitudinally characterizing the open field behavior of female mice across different phases of the estrous cycle, using unsupervised machine learning to decompose spontaneous behavior into its constituent elements1-4. We find that each female mouse exhibits a characteristic pattern of exploration that uniquely identifies it as an individual across many experimental sessions; in contrast, estrous state only negligibly impacts behavior, despite its known effects on neural circuits that regulate action selection and movement. Like female mice, male mice exhibit individual specific patterns of behavior in the open field; however, the exploratory behavior of males is significantly more variable than that expressed by females both within and across individuals. These findings suggest an underlying functional stability to the circuits that support exploration in female mice, reveal a surprising degree of specificity in individual behavior, and provide empirical support for the inclusion of both sexes in experiments querying spontaneous behaviors. Behavioral DataFrames: holds the behavioral syllable data used for the analysis described in the manuscript: mean_df_female / scalar_df_female - main female dataset mean_df_male / scalar_df_male - main male dataset mean_df_female_control / mean_df_male_control - datasets for male/female control experiment presented in Fig S3. Model files: Additional MoSeq model files used for generating FigS2A and FigS2H.