Behavioral question with two closely related variants: (1) 'Describe a project you are particularly proud of' — the interviewer probes deeply into your specific contributions, technical decisions, and outcomes; and (2) 'What is the biggest change/impact you drove?' — focusing on measurable outcomes, cross-functional influence, or a significant shift you caused at your organization. Both variants appear in Waymo Sr. SWE phone screens, sometimes alongside questions about handling conflict and recovering from a project that went wrong.
Common mistakes: Giving a team-level narrative without distinguishing personal contributions; No quantitative results cited; Choosing a project that is too small in scope for a Sr. SWE level; Spending too much time on context/background and not enough on actions and results
What passers do: Crisp STAR structure with quantified outcomes; Clear ownership language ('I decided,' 'I designed,' 'I convinced stakeholders'); Demonstrating cross-team or company-wide impact
Why people fail: Vague answers that don't survive follow-up probing on specifics; Conflating team achievement with personal achievement; Running long on BQ and leaving insufficient time for the coding portion
Edge cases probed: Project that went wrong / failure recovery (asked in same interview); Handling interpersonal conflict (asked in same interview); Debug experience as a form of impact story
Alternative approaches: Resume deep-dive framing (Interviewer may anchor on a specific resume bullet rather than letting the candidate choose; requires candidate to have strong, rehearsed narratives for every listed project.)