A dissertation submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Public Health Research of the Nelson Mandela African Institution of Science and TechnologyMaternal and neonatal mortalities are global public health of concern and are estimated to cause about 830 women deaths every day, of which 99% are from sub-Saharan African countries. In Tanzania maternal and neonatal mortality rate is still alarming. The National health strategic plan for 2008-2015 of Tanzania directed the deployment and trainings of community health workers (CHWs) in provision of maternal, neonatal and child health services. Despite such trainings, yet there is limited evidence of the applicability of the knowledge acquired during trainings when performing their duties. Therefore, this study aimed at determining whether trained CHWs apply learned knowledge when performing their duties so as to improve maternal and neonatal health status. This study, further explored challenges facing community health workers in applying learned knowledge. Under this study both quantitative and qualitative methods were used. Qualitative method used primary data from 30 in-depth interviews with CHWs. Quantitative data were secondary obtained from a cross-sectional survey done to evaluate UNICEF/GoT interventions conducted in thirteen districts of Tanzania in 2007-2010. This study found significant association between age and applicability of learned knowledge among trained CHWs. Community health workers aged above 40 years were more likely to apply the learned knowledge in maternal and child health than those aged below 40 years. Furthermore, this study found several challenges reported to hinder knowledge applicability among CHWs. These include; little participation from community members and local government, shortage of refresher training in maternal and neonatal care, irregular working schedules, unclear roles and responsibilities on neonatal health, heavy workload as well as becoming older and less effective in visiting households, little community member’s participation resulted by jealousy among CHWs and male household heads, mistrust between CHWs and community members as well as social cultural beliefs.