Micro small enterprises (MSEs) face a lot of challenges in the running and growing their business. They need innovative strategies to mitigate those challengers if they are to achieve their organizational goals. The purpose of this research was to examine the effectiveness of institutional interventions and support structures in curbing challenges affecting the growth of MSEs in Tanzanian – case of retail trade businesses in Nyamagana district. The study was guided by four specific objectives. (i) to identify challenges MSEs in retail trade face while conducting their business in Nyamagana District, (ii) to identify the institutional interventions and support structures offered in the operation of the MSEs; (iii) to assess the resultant impacts (effectiveness) of the institutional interventions and support structures on operations of MSEs and (iv) to identify strategies to enhance effectiveness of institutional interventions and support structures to the operations of MSEs The study surveyed 100 retail trade owners/operators (MSEs) using self administered questionnaires and interviewed 13 officials from institutional and support structures, retail trade associations and private service providers. The data from questionnaire was analyses using descriptive statistics with the aid SPSS. The study revealed that MSEs (retail trade businesses) face a number of challenges including limited access to affordable credit (finance), limited entrepreneurial education, lack of access to markers beyond the local areas, high government taxes/charges inability to access market information of the buyers and sellers, limited linkages and business networking and lastly lengthy business registration and licensing procedures. The study further found that a good number of institutional interventions and support structures have been available to MSEs in Nyamagana district to alleviate those challenges but most of them were ineffective in their role to alleviate challenges that MSEs encounter in growing their businesses. The study identified several strategies to enhance institutional intervention and support structures such as government in collaboration with commercial band and microfinance institution developing innovative finance scheme/programs, make use of private sector providers develop and hands-on training programs on entrepreneurship, management and technical skills and reduction tax rates or provide a grace period for start ups and remove requirement to rental l premises, The study recommended to the government to regularly inform the MSEs of the potential and existing support institutions and the Ministry of Small business development to embark on aggressive campaign to promote MSEs to youth and women and other disadvantaged groups including highlighting support institutions and services that are available.