To survive and thrive in their environment, bacteria engage in a multitude of cooperative and competitive behaviours. These behaviours often rely upon the secretion of extracellular public goods that are costly to produce but are essential for effective communication between cells, scavenging of iron and nutrients, protection from biotic and abiotic stresses and engaging in antagonistic competition. These cooperative and competitive behaviours have been studied extensively under controlled laboratory conditions but the extent to which social interactions can drive evolutionary change, shape population structure or promote and maintain diversity in natural bacterial populations remains unclear. In this thesis I explore the extent, form and consequences of social interactions in natural bacterial populations and also how a non-social bacterial trait, the production of functional amyloids, can shape cooperative and competitive dynamics. Using natural soil populations of the bacterium Pseudomonas fluorescens, I explore (1) what drives bacteriocin-mediated competition in these populations by revealing the extent of bacteriocin production in the population and testing whether the strength of interaction is determined by spatial proximity, genetic relatedness or overlap in resource requirements. Using the same isolates I also reveal (2) the extent of potential public goods cheats in the population and demonstrate that potential cheats my be limited in their ability to proliferate by the presence of different forms of public good they cannot utilise. I then take an experimental approach to (3) investigate how a non-social bacterial trait, the production of functional amyloids, can shape cooperator-cheat dynamics in populations of Pseudomonas aeruginosa. I reveal that functional amyloids appear to bind public goods involved in iron acquisition and this may limit their availability to public goods cheats. Finally, I (4) assess the contribution of functional amyloids towards defence against conspecific bacteriocins, revealing that their presence appears to contribute towards individual defence against these toxins but not collective defence.