Entanglement of spatial bipartitions, used to explore lattice models in condensed matter physics, may be insufficient to fully describe itinerant quantum many-body systems in the continuum. We introduce a procedure to measure the Rényi entanglement entropies on a particle bipartition, with general applicability to continuum Hamiltonians via path integral Monte Carlo methods. Via direct simulations of interacting bosons in one spatial dimension, we confirm a logarithmic scaling of the single-particle entanglement entropy with the number of particles in the system. The coefficient of this logarithmic scaling increases with interaction strength, saturating to unity in the strongly interacting limit. Additionally, we show that the single-particle entanglement entropy is bounded by the condensate fraction, suggesting a practical route towards its measurement in future experiments.Traditional two-point correlation functions, and their ability to probe broken symmetries, underlie our modern edifice of condensed matter theory. However, they are known to fail as a foundation for a complete classification of all phases of quantum matter, as demonstrated spectacularly in fractional quantum Hall and other topological phases [1,2]. To remedy this insufficiency, one can construct classifications based on information theory, which is by definition a complete description of all correlations, raising the question of which informationbased quantities are relevant for quantum phases of matter [3]. Bipartite entanglement entropy is a leading candidate, with its usefulness and versatility rapidly increasing along with an understanding of its properties in a variety of quantum phases [4]. For example, the ubiquitous "area law" in the spatial entanglement entropy of the ground state [5,6] has led to ways to classify and characterize quantum phases [7][8][9] and phase transitions [10][11][12] in condensed matter systems, along with elucidating the simulability of quantum models on classical computers [13,14]. Previous work has primarily been based upon modal bipartitions, where the entanglement is between two spatial or momentum subregions. However, in systems of itinerant particles [15], one can choose to bipartition into subsets of particles (Fig. 1) [16][17][18][19][20]. This particle entanglement can give insight into not only quantum correlations due to interaction, but also exchange statistics and indistinguishability [21][22][23].