Which type of professor is most likely to write a strong letter of recommendation?

A professor who served as your research lab supervisor is most likely to write a strong letter of recommendation because they typically have a comprehensive understanding of your skills, work ethic, and academic abilities. In a research lab setting, the supervisor observes your performance closely, allowing them to provide specific examples of your contributions, responsibilities, and how you handle challenges. These insights can make their recommendation more personalized and impactful, showcasing your qualifications in a way that resonates with potential employers or academic programs.

In contrast, a professor who taught your introductory course may not have interacted with you extensively or have a detailed understanding of your capabilities beyond what you demonstrated in a larger classroom setting. A professor you never interacted with would lack the necessary information to provide a personalized recommendation, making their letter less effective. Similarly, a professor from a different department may not be able to speak to your specific skills and experiences relevant to the area you are pursuing, limiting the strength of their recommendation. Thus, the relationship and context a research lab supervisor has with a student create a strong foundation for an effective letter of recommendation.