Whereas the Esperanto vocabulary was drawn from Romance, Germanic, and Slavic languages and others, the vocabulary of Interlingua is drawn mainly from Romance languages. Where the grammar of Esperanto was designed, and contains grammatical elements from wildly disparate languages, the grammar of Interlingua is based solely on the grammar of Romance languages, with some simplification. Interlingua was intended to be, in essence, the "average" of all the existing Romance languages.
The grammar and vocabulary of Interlingua were complete by 1950. Alexander Gode[?] was one of the prime movers in this effort. He published a survey of the grammar, a one-way dictionary (Interlingua to English), and an introductory book entitled Interlingua a Prime Vista ("Interlingua at First Sight").
Interlingua still has some enthusiastic supporters in the United States, the Netherlands, Russia, and particularly Sweden. There are some Interlingua web pages, and at least one monthly newsletter. Interlingua as now used tends to have less Classical Latin vocabulary than Gode's original version, replaced mostly by southern Romance vocabulary. For example emer (to buy) has been replaced by comprar, sed (but) with ma and nimis (too) with troppo.
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The language Romanica is a variant of IALA Interlingua. While Interlingua ditches grammatical gender, adjective/noun agreement and personal verb conjugation, these features are retained in Romanica. The vocabulary is the same, except for adjectives altered by the reintroduction of grammatical gender.