The European honey bee (Apis mellifera) has been present in Australia for approximately 150 years. For the majority of that time it was assumed this species could only be of benefit to Australia‘s natural ecosystems. More recently however, researchers and conservationists have questioned this assumption. Honey bees are an introduced species and may be affecting native fauna and flora. In particular, native bees have been highlighted as an animal that may be experiencing competition from honey bees as they are of similar sizes and both species require nectar and pollen for their progeny. Most research to date has focused on indirect measures of competition between honey bees and native bees (resource overlap, visitation rates and resource harvesting). The first chapter of this thesis reviews previous research explaining that many experiments lack significant replication and indirect measures of competition cannot evaluate the impact of honey bees on native bee fecundity or survival. Chapters two and four present descriptions of nesting biology of the two native bee species studied (Hylaeus alcyoneus and an undescribed Megachile sp.). Data collected focused on native bee fecundity and included nesting season, progeny mass, number of progeny per nest, sex ratio and parasitoids. This information provided a picture of the nesting biology of these two species and assisted in determining the design of an appropriate experiment. Chapters three and five present the results of two experiments investigating the impact of honey bees on these two species of native bees in the Northern Beekeepers Nature Reserve in Western Australia. Both experiments focused on the fecundity of these native bee species in response to honey bees and also had more replication than any other previous experiment in Australia of similar design. The first experiment (Chapter three), over two seasons, investigated the impact of commercial honey bees on Hylaeus alcyoneus, a native solitary bee. The experiment was monitored every 3-4 weeks (measurement interval). However, beekeepers did not agist hives on sites simultaneously so measurement intervals were initially treated separately using ANOVA. Results showed no impact of honey bees at any measurement interval and in some cases, poor power. Data from both seasons was combined in a Wilcoxon‘s sign test and showed that honey bees had a negative impact on the number of nests completed by H. alcyoneus. The second experiment (Chapter 5) investigated the impact of feral honey bees on an undescribed Megachile species. Hive honey bees were used to simulate feral levels of honey bees in a BACI (Before/After, Control/Impact) design experiment. There was no impact detected on any fecundity variables. The sensitivity of the experiment was calculated and in three fecundity variables (male and female progeny mass and the number of progeny per nest) the experiment was sensitive enough to detect 15-30% difference between control and impact sites. The final chapter (Chapter six) makes a number of research and management recommendations in light of the research findings.