This study analyses prepositional errors in Spanska 4 in the Swedish upper secondary school. The analysis focuses on errors regarding the prepositions a, de, en, para and por, as well as errors in sentences without preposition. The aim of this study is to determine which of these prepositions caused most erroneous answers and why. Possible differences according to native language are also analysed. In the investigation 65 students completed a task of filling out the missing prepositions in 24 sentences. The sentences with the preposition a and the sentences without preposition resulted in most erroneous answers. The most common mistake was to answer that there was no need for a preposition where the preposition a should have been used, and vice versa. In these cases, a possible reason for the error was linguistic transfer of the Swedish sentence. Regarding sentences with the preposition de, the students struggled the most with completing them when the preposition did not carry any meaning. Completing sentences with the preposition para was more challenging when it indicated the destination or recipient than when it indicated the intention. Furthermore, it was more common for students to respond with para where the correct answer was por than vice versa.

The aim of the study is to find out to what extent Swedish learners of English, in the first year of upper secondary school, make prepositional errors in their written production, and to what extent these errors can be attributed to negative transfer, overgeneralization and simplification by conducting an Error Analysis. A comparison between gender and type of program, academic and vocational, is made to find out in which type of program most errors appear and if there is any difference in terms of gender.  The data is annotated from the Swedish Learner English Corpus (SLEC), which consists of argumentative essays written by Swedish learners of English, and it consists of 24 randomly selected texts based on the variables binary gender, type of program, Swedish as their L1, school year, and English course. All the texts selected are written by students in the first year of upper secondary school studying the course English 5. The results of the study reveal that Swedish learners of English struggle with prepositional usage. In total, 649 prepositions were identified in the 24 texts. Out of these, 72 (11.09%) were used incorrectly. The most frequently used prepositions involved in these errors are of, for, in, to, and with. Most errors appear when prepositional phrases function as post-modifiers in noun phrases. Substitution is, by far, the most common type of error found, meaning that the students replace the correct preposition with an incorrect one. The results thus show that the students seem to be aware that a preposition should be used although they fail to choose the correct one. Female students make more prepositional errors than male students; similarly, students attending vocational programs make more prepositional errors than students attending academic programs. Most errors are cases of overgeneralizations, followed by negative transfer from Swedish, and simplification. However, many of the errors can still be attributed to negative transfer which suggests that, even though Swedish and English are similar languages which could lead to positive transfer, this does not seem to fully apply to prepositions.