What the Evidence Actually Shows
Sam Millunchick · 3 Meta-Analyses · 70+ Sources · February 2026
Moderate positive effect size across three independent meta-analyses of randomized controlled trials. Comparable to psychotherapy effect sizes.
De Haan & Nilsson 2023 · Nicolau et al. 2023 · Cannon-Bowers et al. 2023
Executive coaching sits at the intersection of organizational psychology, leadership development, and adult development theory. The first Coaching Psychology Unit was established in 2000. Rigorous research has accumulated meaningfully only in the last 15 years.
The 80/20 of what the research shows
The working alliance — agreement on goals, tasks, and the bond between coach and coachee — is the most consistent predictor across all studied populations. This mirrors 50+ years of psychotherapy research on common factors.
Personality matching between coach and coachee is not supported by the evidence. What matters is the relationship that develops, not demographic or personality similarity.
Source: Nicolau et al. 2023. Behavioral wins create momentum, build self-efficacy, and often pull attitudes along behind them.
"What will you do differently in the next meeting?" is more powerful than "How do you need to think differently about leadership?"
Coachee self-efficacy and readiness for change predict outcomes at least as strongly as anything the coach does. Coaching is not something done to someone.
"Forced coaching" is a fundamentally different proposition. When readiness is low, the first phase of coaching should focus on building readiness — not jumping to behavior change.
GROW, Co-Active, Solutions-Focused, Cognitive-Behavioral — no specific methodology has been shown to be reliably superior. Most share the same active ingredients: goal-setting, reflective questioning, accountability, a supportive relationship.
"Commit yourself heart and soul to your approach, even if you know that it doesn't matter which professional approach you choose." Erik de Haan — Relational Coaching
Adding skills at the same level of complexity
Increasing the sophistication of how someone makes meaning
Kegan & Lahey's framework (2009). Strong theoretical base, but limited RCT evidence specific to coaching applications. Emerging
Three meta-analyses published in 2023
⚠ De Haan & Nilsson flag "indications of significant publication bias." True effect size may be smaller. Trim-and-fill adjusted: g = 0.27.
Coach selection should focus on relational capacity and skill, not "fit" questionnaires or personality matching.
Appears in all three meta-analyses. Likely reflects measurement limitations — most studies cluster in the 6–12 session range. Quality of sessions likely matters more than quantity.
g = 0.48 face-to-face vs g = 0.35 virtual — not statistically different (Cannon-Bowers 2023).
Larger effects with qualified coaches in non-leadership contexts. But evidence that credentialing predicts better outcomes is thin. Emerging
Evidence-grounded moves you can use
Where is the coachee stuck? Most coaching failures happen because coaches apply "more of the same" instead of diagnosing which condition is missing.
From David Peterson (Google). A coachee with insight and motivation but lacking capabilities needs teaching, not more reflective questions. Moderate
For executives who know what to do but can't seem to do it. The closest coaching gets to therapeutic depth without crossing the therapy line.
Kegan & Lahey (2009). Moderate
What the critics say — and where they're right
Negative effects are real but uncommon: dependency on coach, worsening supervisor relationships when the coachee changes but the system doesn't, reduced job satisfaction when coaching reveals values-job misfit. Schermuly & Graßmann, 2019
Decision translation — what changes if this is true
Full source log with 70+ references available in the complete research document.
High-stakes communication coaching for founders and executives
Executive Coaching Methods — What the Evidence Actually Shows
February 2026 · 3 Meta-Analyses · 70+ Sources