ACS In-Text Citations
Master ACS (4th edition) in-text citations with this complete guide. Learn the correct format for every scenario, including single and multiple authors, direct quotes, and sources with missing information.
In-Text Citation Rules
Below are the ACS in-text citation rules for every common scenario you will encounter when writing your paper.
Single Author
Superscript italic number after punctuation¹ (order-of-citation) or (Smith, 2024) for author-date
Two Authors
Same superscript number or (Smith and Jones, 2024)
Three or More Authors
Same superscript number or (Smith et al., 2024) for 3+ authors
Direct Quote
Superscript number or (Smith, 2024, p 15) — page numbers cited when needed
No Author
Use organization name or abbreviated title; numbered in order of appearance
No Date
(Smith, year unknown) or include the best available date estimate
Quick Examples
Here are real-world ACS in-text citation examples for different source types:
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Cite in ACS Now →Frequently Asked Questions
- How do I format an ACS in-text citation?
- For a single author in ACS, use the format Superscript italic number after punctuation¹ (order-of-citation) or (Smith, 2024) for author-date. For two authors, use Same superscript number or (Smith and Jones, 2024). For three or more authors, use Same superscript number or (Smith et al., 2024) for 3+ authors.
- How do I cite a direct quote in ACS?
- For direct quotes in ACS (4th edition), use the format: Superscript number or (Smith, 2024, p 15) — page numbers cited when needed.
- What if there is no author or no date in ACS?
- When there is no author in ACS, use: Use organization name or abbreviated title; numbered in order of appearance. When there is no date, use: (Smith, year unknown) or include the best available date estimate.