Education leaders and political leaders worldwide are increasingly placing greater emphasis on developing scientific literacy in response to OECD’s PISA testing. This is also the case in Wales where the results of the 2009 and 2012 scientific literacy tests were significantly lower than the rest of the United Kingdom. This thesis considers interpretations of the term scientific literacy in Wales, including confusion over what the term actually means and an exploration of the potential of renaming it ‘scientific competency’ in order to minimise issues regarding current definition. An alternative definition is considered, in addition to an exploration of the current methods of measuring and improving it within the country. A post-positivist approach was adopted in the research. Data were collected through questionnaires, semi-structured interviews and a case study. The analysis of data revealed that Welsh science teachers often had inadequate skills and understanding regarding scientific literacy and this impacted directly upon their ability to measure and improve it within their lessons. This was due to teachers’ perception of a lack of guidance and training. Although there was substantial consensus about the importance of science and scientific literacy to pupils, this was not adequately translated into scientific literacy practices within schools. Large scale educational reform has led to an emphasis on literacy and numeracy skills, but there has been limited focus on science education. In addition, the Welsh education system and its lack of standardised testing may have produced a lack of rigor within science, leading to a decrease in attainment. The study has implications for the professional development of Welsh science teachers and the general teaching of Science within the country and beyond.