The main purpose of this study was to assess attitudes of teachers on the effectiveness of Tanzania teachers union (TTU) in improving teachers’ welfare of public primary and secondary schools in Dodoma City Council, Tanzania. The research was guided by four specific objectives which are to determine members attitudes toward Tanzania teachers union, to examine the effectiveness of TTU in fulfilling its duties and improving members welfare, to explore possible challenges that union and members are facing in the union and lastly to find out possible measures that can be taken to solve challenges in the union. The study was guided by Social capital theory. Mixed research approaches were employed by using convergent parallel design. The study used n=64 respondents which comprising 14 TTU administrators, 20 public secondary school teachers and 30 public primary school teachers. Questionnaires and interview were used to collect data. Data were obtained and analysed using Statistical Package for Social Sciences (SPSS) version 20 computer package. Data used descriptive statistics and the findings were presented by the use of frequency tables and pie-charts. Qualitative data was coded, categorized and analysed using a thematic approach, of which description was employed to present data in chapter four. Study found that Tanzania teachers’ union effectiveness in improving teachers’ welfare is as a result of the performance of the union to the members, the union is not doing enough in improving teachers’ welfare because of several factors like corruption in the union and incompetent TTU administrators. Researcher recommended that the union should arrange a timetable for several meetings with teachers in their schools to listen to their opinions on what they suggest to be done in the union for their welfare improvement. Study recommends that, TAMISEMI as employer should work in partnership with TTU so as to help them in vi improving teachers’ welfare. This to some extent will help to clear the image of the union to its members for posterity.