The recent literature has shown the importance of preservice elementary science teachers (PESTs) having a deep understanding of argumentation, as this factor may affect the nature of the class activities that are taught and what students learn. A lack of understanding of this factor may represent an obstacle in the development of science education programmes in line with the development of scientific competences. This paper presents the results of the design and implementation of a training programme of 6 sessions (12 h of class participation plus 8 h of personal homework) on argumentation. The programme was carried out by 57 Spanish PESTs from Malaga, Spain. The training programme incorporates the innovative use of certain strategies to improve competence in argumentation, such as teaching PESTs to identify the elements of arguments in order to design assessment rubrics or by including peer assessment during evaluation with and without rubrics. The results obtained on implementing the training programme were evaluated based on the development of PESTs' argumentation competence using Toulmin's argumentative model. Data collection methods involved two tasks carried out at the beginning and the end of the programme, i.e., pre- and post-test, respectively. The conclusion of the study is that students made significant progress in their argumentation competence on completing the course. In addition, PESTs who followed the training programme achieved statistically better results at the end than those in the control group (n = 41), who followed a traditional teaching programme. A 6-month transfer task showed a slight improvement for the PESTs of the experimental group in relation to the control group in their ability to transfer argumentation to practice.