Vocabulary research has followed a different path in English and in Spanish applied linguistics. Spanish applied linguistics has paid more attention to available lexicons of speakers than to word frequency. The measure of lexical availability combines the frequency at which a word is produced as a member of a semantic category (e.g. dog in category Animals) and the position in the list of associations provided by a group of individuals. It focuses on the words retrieved by speakers in response prompts (word stimulus) related to daily situations. This paper intends to present some of the aspects of lexical-availability research that are interesting for L2 vocabulary acquisition. It attempts to show the potential of lexical-availability research as an alternate approach for vocabulary planning (the use of L1 lexical-availability measures to select the teaching vocabulary for L2) as well as the study of some psycholinguistic aspects of vocabulary acquisition, such as the organization of learners' mental lexicons, the similarities and the differences between response patterns, the kinds of semantic associations that learners activate in response to prompts (semantic categories), the consideration of the most available words obtained by lexical-availability research as semantic prototypes. Likewise, the study of learners' lexical availability can uncover sociolinguistic and cultural issues. Furthermore, this paper wishes to inspire researchers of languages other than Spanish to apply this methodology to different languages. All these aspects are hereby presented on the basis of the Slovene learners' available lexicons in Spanish as L2 (N=200) (Sifrar Kalan, 2009; 2012; 2014b) and English as L2 (N=20) (Sifrar Kalan, 2014a). Keywords: foreign languages, vocabulary acquisition, lexical availability, word associations