Introduction: The HPTN 071 (PopART) trial is a community randomised trial in Zambia and South Africa, examining the impact of combination prevention, including treatment as prevention using Universal Test and Treat (UTT), on community level HIV-incidence. This PhD evaluates the factors associated with uptake of the key interventions, during the first year of the trial. Methods: Two systematic reviews were conducted on home-based HIV testing and counselling (HB-HTC), and the cascade-of-care following community-based HTC, respectively. In addition, two case-control (CC) studies were nested within PopART, to examine factors associated with the uptake of the door-to-door home-based universal testing (CC study 1), and universal treatment (CC study 2) interventions. Results: Our results suggest that HB-HTC in sub-Saharan Africa is widely accepted – uptake among those offered HB-HTC was 83% in a systematic review and meta-analysis of studies (2000-2012). The second systematic review found considerable variability in measures used to report linkage-to-care and ART initiation and in outcomes reported, even for similar time periods following HIV-detection (studies between 2006-2016). CC1 found no differences between acceptors and non-acceptors of HB-HTC by demographic and behavioural characteristics. CC2 identified that the more lifetime sexual partners participants reported, the more likely they were to achieve timely linkage and ART initiation (TLA). Negative perceptions about clinic infra-structure were associated with failure to achieve TLA. Both CC studies found that favourable views about the Community HIV-care Providers was associated with uptake of interventions, while neither stigma nor unfavourable views about clinic staff were associated with uptake. Conclusion: This PhD contributes to knowledge on the cascade-of-care and UTT. It suggests that PopART interventions are acceptable across population sub-groups, providing optimism for achieving universal coverage using the PopART model to implement UTT. If individuals with high-risk sexual behaviour embrace interventions as we observed, there is great promise for treatment as prevention.