Here are the guidelines for chart titles in ASA style:
* Placement: Place the chart title directly below the chart.
* Capitalization: Capitalize the first letter of each word in the title (except for prepositions, articles, and conjunctions).
* Font: Use the same font as the rest of your essay.
* Style: Use a clear, concise, and descriptive title that accurately reflects the content of the chart.
Example:
```
Chart 1. Average Annual Rainfall in Seattle, Washington (1990-2020)
```
Remember that ASA style prioritizes clarity and conciseness. While underlining might seem visually appealing, it's unnecessary and can detract from the overall professionalism of your essay.