How do I assess soft skills in an interview?

Because the thing being measured is never defined. A scorecard line reading communication invites each interviewer to rate whatever they associate with the word: fluency, warmth, brevity, confidence. Those correlate with accent, extroversion and cultural familiarity far more than with the job. The second failure is accepting stories at face value. Candidates arrive with polished narratives, and without follow-up questions you learn who rehearsed rather than who did the work. The third is timing: soft skills get discussed at the end of the debrief when the technical decision is already made, so they function as a tiebreaker driven by impression rather than as an assessed competency. Each of those failures is fixable, and none of them needs a new assessment product to fix.

Translate it into behaviour in the context of this role. Communication for a support engineer might mean explaining a technical constraint to a frustrated non-technical customer without over-promising. For a team lead it might mean delivering critical feedback that changes behaviour without damaging the relationship. Those are different skills that share a label. Write the definition into the scorecard with anchors for strong and weak evidence, then design one question that targets it directly. A useful test of your definition: could two interviewers who never spoke agree on a rating from the same transcript. If not, the definition is still an adjective. Write the definition into the scorecard before the first interview, not after the debrief argues about it.

Past-behaviour questions followed by persistent probing. Ask for a specific instance, then establish the details: what was the situation, what did you personally do, what did others do, how did the other person react, what happened next, what would you change. The follow-ups do the work. A rehearsed answer collapses at the third question because the specifics were never there. Ask for a time it went badly as well as a success, since the failure story reveals self-awareness that success stories are designed to hide. Keep the same questions across every candidate for the role so the answers are comparable, which is the whole point of structured interviewing. Take notes in the candidate's own words, since paraphrase quietly removes the detail you will need later.

Yes, and it is stronger evidence. A short work simulation shows collaboration and communication in a way stories cannot: a design discussion where the interviewer pushes back, a written exercise producing something the role actually requires, a role-play of a difficult customer conversation for a support hire. Watch how the person handles disagreement, whether they ask clarifying questions, and how they explain their reasoning. Keep it realistic and time-boxed. Combine one simulation with one behavioural interview and score both against the same anchors. Record the evidence in your hiring software so the debrief works from what happened rather than from how everyone felt. Tell candidates what the exercise involves in advance, so you are testing the skill rather than their reaction to a surprise.