Dequeísmo: 'pienso de que' (error)

Pienso que es una buena idea. Me alegro de que hayas venido. The first sentence has no de before que; the second requires it. The difference is dictated by the governing verb: pensar que is bare, alegrarse de que is not. The two parallel errors that consist of getting this wrong have official names and are the focus of more usage-correction in Spanish than any other point of syntax.

Dequeísmo is inserting de before que when no preposition is licensed by the governing verb (pienso de que…, creo de que…, me dijo de que…). Queísmo is the opposite error — omitting de (or another preposition) before que when the governing verb does require it (me alegro que…, me acordé que…, estoy seguro que…). Both errors are widespread in spoken peninsular Spanish; both are corrected in education, media, and formal writing; both are stigmatised, with dequeísmo carrying the heavier social weight (it is the one that gets you publicly mocked).

This page explains how to diagnose each error with a single substitution test, lists the high-frequency verbs and adjectives on each side, and gives the peninsular usage notes so you can avoid both pitfalls. Getting these patterns right is a clear marker of educated peninsular Spanish.

What dequeísmo is

Dequeísmo (from de que) is the insertion of de before a que-clause that follows a verb that does not require any preposition. The verbs most commonly hit by dequeísmo are everyday assertion and cognition verbs: pensar, creer, decir, opinar, considerar, suponer. None of these take any preposition before their que-complement; inserting de is ungrammatical.

Dequeísmo is especially stigmatised in Spain. It marks the speaker as either uneducated or pretentious (trying to sound formal and overshooting). Spanish-language media regularly mock politicians, athletes, and television presenters who fall into dequeísmo, and the RAE explicitly lists it as a "vicio del lenguaje." Avoiding it is the single biggest spoken-Spanish hygiene gain for any learner.

The root cause of dequeísmo is hypercorrection: speakers know that many verbs do require de (acordarse de, alegrarse de, darse cuenta de), and they over-extend the pattern to verbs that don't.

What queísmo is

Queísmo is the mirror error: omitting the de (or another preposition) before que when the governing verb or adjective genuinely requires it. The verbs and adjectives most commonly hit by queísmo are pronominal verbs and adjectives that lexically select a preposition: acordarse de, alegrarse de, darse cuenta de, olvidarse de, estar seguro de, ser consciente de.

Queísmo is somewhat less stigmatised than dequeísmo in spoken Spain — estoy seguro que viene is heard so often that many speakers do not register it as wrong — but it remains a clear error in formal writing and in educated speech. The RAE flags it alongside dequeísmo as a usage problem.

The root cause of queísmo is simplification: speakers economise by dropping the preposition, especially in verbs where the de is short and easily skipped over.

The diagnostic: the eso substitution test

The single best diagnostic for both errors is to replace the que-clause with eso and see whether the resulting sentence requires the preposition or not.

The logic: a que-clause and the pronoun eso fill the same grammatical slot. Whatever preposition the verb requires before eso is the preposition it requires before the que-clause. If eso needs no preposition, neither does que.

Worked examples

Pensar. Pienso eso — grammatical, no preposition. → Therefore pensar que, not pensar de que. (❌pienso de que.)

Creer. Creo eso — grammatical, no preposition. → Therefore creer que, not creer de que. (❌creo de que.)

Decir. Lo digo / digo eso — grammatical, no preposition. → Therefore decir que, not decir de que. (❌digo de que.)

Alegrarse. Me alegro de eso — required with de. (❌me alegro eso would be wrong.) → Therefore alegrarse de que, not alegrarse que. (❌me alegro que.)

Acordarse. Me acuerdo de eso — required with de. → Therefore acordarse de que. (❌me acuerdo que.)

Estar seguro. Estoy seguro de eso — required with de. → Therefore seguro de que. (❌seguro que in the sense "I'm sure that…"; note that bare seguro que exists as a separate adverbial use, "surely / I bet" — see below.)

A second test: the question form

When the que-clause functions as the answer to a question, the question word reveals whether the verb takes a preposition.

• ¿Qué piensas? — bare qué, no preposition. → Pensar que (no de).
• ¿De qué te alegras? — de qué, preposition required. → Alegrarse de que.
• ¿De qué te acuerdas? — de qué, preposition required. → Acordarse de que.
• ¿De qué estás seguro? — de qué, preposition required. → Estar seguro de que.

If you can ask ¿de qué…?, the verb takes de. If you can only ask ¿qué…?, the verb takes no preposition.

Verbs and adjectives that REQUIRE de before que

This is the queísmo-trap list: omitting de before any of these is the queísmo error.

Pronominal verbs (almost always se + verb + de)

Non-pronominal verbs and verb phrases

A note on advertir: both advertir de que and advertir que are accepted by the RAE, with a slight semantic split — advertir de que leans toward "warn about the fact that," advertir que toward "perceive that." In peninsular use, both are heard.

Adjectives that require de

Nouns that take de que

A handful of nouns whose complement clause requires de:

• la idea de que — "the idea that"
• el hecho de que — "the fact that"
• el rumor de que — "the rumour that"
• la posibilidad de que — "the possibility that"
• la sensación de que — "the feeling that"
• la convicción de que — "the conviction that"
• la duda de que — "the doubt as to whether"

Verbs that do NOT take de before que

This is the dequeísmo-trap list: inserting de before any of these is the dequeísmo error.

Note the contrast between acordarse de que (with de) and recordar que (without). These two verbs mean almost the same thing, but they have different syntactic properties: acordarse is pronominal and selects de; recordar is non-pronominal and takes no preposition. This is the single most reliable trap: speakers who know that acordarse takes de sometimes assume that recordar does too. It doesn't.

The special case: seguro que as an adverbial

A subtlety worth flagging. Seguro de que (with de) is the regular adjective + complement clause construction: estoy seguro de que viene = "I'm sure that he's coming." But there is also a separate, bare seguro que… construction that functions as an epistemic adverbial, equivalent to "surely / I bet…":

This is not queísmo. In this use, seguro is functioning as an adverb-like sentence-modifier, not as the adjective complement of a copula. The two constructions are distinct, and seguro que viene (adverbial) is fully grammatical even though estoy seguro de que viene requires the de. Native speakers shift fluidly between them.

A similar adverbial use exists with lo más probable es que / probablemente / posiblemente — none of these require any preposition before the que-clause, because the matrix is not a verb + complement structure but an adverbial scaffolding.

Peninsular usage notes

In peninsular speech, dequeísmo is most visible in:

• Football and sports commentary: yo pienso de que el árbitro se equivocó.
• Live broadcasts under time pressure: politicians and television presenters fall into it under stress.
• Speakers consciously trying to "sound formal" — the hypercorrection effect.

Queísmo is most visible in:

• Casual conversation, especially with me alegro que, estoy seguro que, me doy cuenta que.
• Spoken peninsular Spanish more than written — many speakers who write me alegro de que will say me alegro que without noticing.

In writing — formal letters, essays, professional emails, journalism — both errors are clearly marked and corrected by editors. In careful spoken Spanish (a job interview, a presentation, a courtroom appearance), both are avoided. Spanish-language education in Spain spends substantial time on this point, and educated peninsular Spanish keeps both at bay.

Common Mistakes

Key takeaways

• Dequeísmo = inserting de before que with verbs that don't require it (❌pienso de que, ❌creo de que, ❌me dijo de que). Strongly stigmatised in Spain.
• Queísmo = omitting de (or another preposition) before que with verbs and adjectives that require it (❌me alegro que, ❌estoy seguro que, ❌me acordé que). Less stigmatised in speech but clearly an error in writing.
• The diagnostic: replace the que-clause with eso. If you'd naturally say eso with no preposition, the verb takes que with no preposition. If you'd say de eso, the verb takes de que.
• Always de que with: acordarse de, alegrarse de, darse cuenta de, asegurarse de, olvidarse de, enterarse de, estar seguro de, consciente de, capaz de, harto de, la idea de, el hecho de, el rumor de.
• Never de que with: pensar que, creer que, decir que, opinar que, sostener que, afirmar que, suponer que, saber que, ver que, oír que, recordar que.
• Watch the acordarse de que vs. recordar que contrast — they mean almost the same thing but have opposite syntactic patterns.
• Bare seguro que… as an adverbial ("I bet…") is not queísmo — it's a distinct construction. Estoy seguro de que… with the copula requires de.