**Background:** Preregistration, (i.e., publicly registering hypotheses and methods before collecting data), has been proposed as a means to reduce “questionable research practices” and biases which are thought to result in high rates of false positives and inflated effect sizes in the literature. Additionally, Registered Reports have been developed as a format that incorporates the benefits of preregistration and also reduces publication bias by basing a journal’s decision to accept a manuscript for publication on the quality of the preregistration before results are known. Both “simple” preregistration and Registered Reports are used by a growing number of psychological researchers, but it is currently unknown if, or to what extent, the two formats’ safeguards against bias affect the reported research outcomes. **Objective:** The primary goal of this study is to descriptively assess the proportion of confirmed hypotheses and the effect sizes reported in preregistered studies and Registered Reports. In order to facilitate future efforts to disentangle the “pure” effects of these publication formats from potential confounding factors, a secondary goal is to explore any relevant characteristics of the types of research for which the two formats are currently used. **Method:** At least two independent coders will identify the confirmatory hypotheses, analyses, and conclusions reported in each article. The proportion of confirmed hypotheses will be calculated by dividing the number of confirmed hypotheses (according to the respective authors) by the total number of hypotheses. Effect sizes will be coded for each hypothesis and analysed using a multi-level meta-analysis of dependent effect sizes. **Population:** Eligible studies have to report primary research (i.e., excluding meta-analyses) in psychology. We will analyse the full population of Registered Reports published before 19th June 2018 and the full population of two types of preregistered studies published before 19th June 2018: (1) articles with a “Preregistered Badge”, and (2) articles judged to be eligible for the “Preregistration Challenge prize” by the Center for Open Science.