Negotiation activity, as a social interaction kind, is grounded on a proposal sequence. A proposal projects an admission or a dismissal as the possible next action, and response particles emerging in this position may be heard accordingly. This study explores Finnish response particles as a negotiation resource. Using conversation analysis, it examines the particles mm, jaa and joo which constitute whole turn-constructional units as responses to proposals. The study demonstrates that they form a continuum with mm at one end as the least propitious response particle and joo at the other end as the most propitious. Even the most motivating particle joo though is not enough to achieve proposal acceptance on its own: a clear acceptance or further development of the proposal is required after the joo.