In recent decades, the classical methods of studying the psychometric properties of tests have advanced to evolve into new innovative statistical methods, which allows obtaining a new view of the data. In this sense, progress has been made in the use of item response theory and in the use of structural equation models. Likewise, classical statistical inference methods have advanced in hypothesis testing and Bayesian statistics is rapidly making its way both in experimental studies and in psychometric studies. The aim of this issue has been to contribute to the dissemination of new research methodologies in quantitative and qualitative analysis in Psychology, as well as to evaluate the effectiveness and advantages of the new methods compared to classic psychometric tools and methods. Manuscripts on methodological issues of current interest, meta-analyses or systematic reviews, articles that introduce new applications on various procedures used in solving problems in Psychology, and reviews of statistical software have been welcomed. Likewise, researchers from other areas were invited to make presentations in which the relevance for psychology of the procedures developed in other fields could be verified. In this issue, 17 manuscripts have been submitted, of which 12 have been accepted. A total of 34 authors have participated in this special issue. We can see that four types of manuscripts have been published: (1) Development of scales and psychometric validation studies, (2) Theoretical and/or opinion articles, (3) Simulation studies, and (4) Systematic reviews or meta-analysis.