This proposal studies statistical investigations as tools to promote statistical thinking and critical citizenship in the process of professional development for mathematics teachers. A qualitative methodology with a critical dialectical approach was followed. The information was produced within a professional development for in-service teachers from a public school in the northwest of Colombia. A statistical investigation that addressed CO2 emissions was implemented, and teachers of different teaching levels explored real data from the World Bank by using CODAP software. The units of analysis were the interactions of the teachers with their colleagues during the professional development. The main results exhibit evidence of statistical thinking and critical citizenship in mathematics teachers during the course of the empirical inquiry.