Following a cognitively-oriented framework, this study builds upon the authors' previous work (Elola and Mikulski 2013; Mikulski and Elola 2011), which analyzed writing processes (planning time, execution time, revision time), fluency, and accuracy of Spanish heritage language (SHL) learners when composing in English and in Spanish. By analyzing Spanish foreign language (SFL) learners' writing processes when composing in English and Spanish, the current study compares writing behaviors in both languages within the SFL group, as well as provides a comparison between the writing behaviors of the SHL and SFL learners completing the same writing tasks. SFL learners wrote less fluently, performed more surface revisions, and demonstrated less accuracy when writing in Spanish than in English, but monitored more in English. However, they allocated similar amounts of time to execution and planning across languages. Compared to their SHL counterparts, SFL learners wrote less fluently and accurately and devoted less time to Spanish intersentential planning and English monitoring. The SFL learners performed more surface revisions in Spanish and fewer meaning revisions in English and Spanish than the SHL learners. Insights into cross-linguistic transfer of writing skills and pedagogical suggestions are provided.