Experiments with artificial microbial communities indicate that certain community compositions are more resistant to microbial invasion than others. However, few invasion experiments have used natural microbial communities to investigate how the effect of community composition on invasion resistance relates to different aspects of community growth. We conducted experimental invasions of two bacterial species (Pseudomonas fluorescens and Pseudomonas putida) into 678 bacterial communities, comparing composition to several aspects of community growth prior to invasion to see how well they predicted invasion. We show that even in these complex microbial assemblages, the effects of resident community composition and growth are largely overlapping -with parameters associated with the productivity of the community (cell yield, community respiration) emerging as the main limiting factors for invasion success. Despite their complexity, these communities can be classified into a few compositional groups that are associated with the main differences in community growth, and thereby invasion resistance.