Because the Spanish subjunctive mood is so variable and does not adhere to a straightforward set of rules, research about its everyday uses by native speakers is very useful and enlightening for learners of the Spanish language. This particular study focuses on several matrices that have exhibited variation in other studies on the topic such as no pensar que, no creer que, dudar que, no dudar que, creer en la posibilidad de que, alegrarse de que, and dar pena de que. This study found that the second language learners (SLLs) demonstrated more variability regarding subjunctive/indicative mood selection than the native speakers and differed with the native speakers mainly regarding the matrices no dudar que, dudar que, es seguro que, and alegrarse de que. Furthermore, no particular characteristic, gender, age, nationality, L1, length of time spent in Spain, length of time studying Spanish, nor interaction with native speakers proved to cause a closer approximation to the mood selection of the native speakers. Even so, this thesis explores the daily uses of the subjunctive/indicative moods in Spanish by native speakers, and offers a clearer understanding of the SLL mood selecting process and justifications, shedding light on the uncertainty of the subjunctive mood in Spanish